<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:15a7cbfa-01ca-4e74-9939-1b36e8667f54,g:312a409e-35b6-4284-b9f6-1a82050d2c4e-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://www.costar.com/role/Coverpage" xlink:type="simple" xlink:href="csgp-20201231.xsd#Coverpage"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/Coverpage" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_fff52317-9731-4c61-aaef-0eb7f99a4073" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_6a023f6c-b80a-4bd1-abea-a9f85fd8c514" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_fff52317-9731-4c61-aaef-0eb7f99a4073" xlink:to="loc_us-gaap_SellingAndMarketingExpense_6a023f6c-b80a-4bd1-abea-a9f85fd8c514" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost_ff88239b-7240-46b2-8c8e-073b45bc4210" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_fff52317-9731-4c61-aaef-0eb7f99a4073" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseSoftwareExcludingAcquiredInProcessCost_ff88239b-7240-46b2-8c8e-073b45bc4210" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_9e4cff94-f9ba-4569-82bd-18491317ff1b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_fff52317-9731-4c61-aaef-0eb7f99a4073" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_9e4cff94-f9ba-4569-82bd-18491317ff1b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_50bce50f-4afc-4544-928a-43c4d7d21778" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_fff52317-9731-4c61-aaef-0eb7f99a4073" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_50bce50f-4afc-4544-928a-43c4d7d21778" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_0ca8e047-773a-49b2-a2cc-fa62bfb1b051" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5d8c1a5d-72d3-40b8-a942-c9a5aebd5253" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_0ca8e047-773a-49b2-a2cc-fa62bfb1b051" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5d8c1a5d-72d3-40b8-a942-c9a5aebd5253" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_b506e088-442f-4b16-a223-d8a7d127db18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_0ca8e047-773a-49b2-a2cc-fa62bfb1b051" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_b506e088-442f-4b16-a223-d8a7d127db18" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_62455a95-bc12-44c8-ac42-83c0ed774f54" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5cd48ff5-7618-41cd-ba9a-990950fe5cc0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_62455a95-bc12-44c8-ac42-83c0ed774f54" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5cd48ff5-7618-41cd-ba9a-990950fe5cc0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_fd293f60-93dc-412b-87f5-6ab8b5759cde" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_62455a95-bc12-44c8-ac42-83c0ed774f54" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_fd293f60-93dc-412b-87f5-6ab8b5759cde" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6117d358-c3e4-4a26-8776-b524e7246b2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_InterestAndOtherIncomeNet_e196e7bc-b46e-46cb-a6ca-3d991248ab19" xlink:href="csgp-20201231.xsd#csgp_InterestAndOtherIncomeNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6117d358-c3e4-4a26-8776-b524e7246b2f" xlink:to="loc_csgp_InterestAndOtherIncomeNet_e196e7bc-b46e-46cb-a6ca-3d991248ab19" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_367fa0ed-0550-4ee2-b00a-d73ea114bedd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6117d358-c3e4-4a26-8776-b524e7246b2f" xlink:to="loc_us-gaap_OperatingIncomeLoss_367fa0ed-0550-4ee2-b00a-d73ea114bedd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_InterestAndOtherExpenseNet_200552df-eaa5-4765-9873-843af60a460d" xlink:href="csgp-20201231.xsd#csgp_InterestAndOtherExpenseNet"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_6117d358-c3e4-4a26-8776-b524e7246b2f" xlink:to="loc_csgp_InterestAndOtherExpenseNet_200552df-eaa5-4765-9873-843af60a460d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c04722f7-e850-42d0-8521-41f760f44b46" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_57fb0168-6745-457e-b238-20f2a4d1c86f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c04722f7-e850-42d0-8521-41f760f44b46" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_57fb0168-6745-457e-b238-20f2a4d1c86f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_6e0c1256-d5c7-444d-a00e-fa299b906632" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c04722f7-e850-42d0-8521-41f760f44b46" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_6e0c1256-d5c7-444d-a00e-fa299b906632" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_ff0c36d2-0542-454e-8020-c01f5a89d742" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c04722f7-e850-42d0-8521-41f760f44b46" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_ff0c36d2-0542-454e-8020-c01f5a89d742" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_bc26e16e-9972-452f-82f4-682902d22f72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_ec57d2e2-f6cd-4619-a2ad-5e7637f683d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_bc26e16e-9972-452f-82f4-682902d22f72" xlink:to="loc_us-gaap_NetIncomeLoss_ec57d2e2-f6cd-4619-a2ad-5e7637f683d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_3f65dae6-df9c-496c-b40d-d022b0852904" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_bc26e16e-9972-452f-82f4-682902d22f72" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_3f65dae6-df9c-496c-b40d-d022b0852904" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_d37037d1-b0de-48b7-907f-2bfb92f2c88d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:to="loc_us-gaap_PreferredStockValue_d37037d1-b0de-48b7-907f-2bfb92f2c88d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_8ede7c1e-4aab-4bd0-bc87-04997c045010" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:to="loc_us-gaap_CommonStockValue_8ede7c1e-4aab-4bd0-bc87-04997c045010" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_c75fe071-948e-4d90-806a-2ba45e38dc10" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:to="loc_us-gaap_AdditionalPaidInCapital_c75fe071-948e-4d90-806a-2ba45e38dc10" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_fa3c2f8f-683e-4260-a9c4-063b932c877d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_fa3c2f8f-683e-4260-a9c4-063b932c877d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_be9406c2-eb45-4bb0-a4b6-0acedc9ed658" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_2a64f7a9-59f5-42a1-ba57-622c6b64cf4e" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_be9406c2-eb45-4bb0-a4b6-0acedc9ed658" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_b06cc750-5da1-45ec-b62b-b3c9bbc74bae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_AssetsCurrent_b06cc750-5da1-45ec-b62b-b3c9bbc74bae" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_56f68730-15cb-440e-b5fb-206c3698527f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermInvestments"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_LongTermInvestments_56f68730-15cb-440e-b5fb-206c3698527f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_4592329c-0400-4e03-9252-1cd86359f960" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_4592329c-0400-4e03-9252-1cd86359f960" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_45b57227-3cfe-447c-8b0f-1783dd6f32f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_45b57227-3cfe-447c-8b0f-1783dd6f32f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_c1ee50fd-2d41-42f2-9625-09afd6671b45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_c1ee50fd-2d41-42f2-9625-09afd6671b45" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_b66ecf3f-db02-4ac3-b857-e89edfe29f53" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_Goodwill_b66ecf3f-db02-4ac3-b857-e89edfe29f53" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_e6414645-e358-40de-8cd7-7f74777655fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_e6414645-e358-40de-8cd7-7f74777655fc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCosts_d55130b4-db33-4ad2-a207-946609890ed5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCosts"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_DeferredCosts_d55130b4-db33-4ad2-a207-946609890ed5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsAssetsNoncurrent_4d296c3a-a741-4a6d-96b5-623084cc3912" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepositsAssetsNoncurrent"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_DepositsAssetsNoncurrent_4d296c3a-a741-4a6d-96b5-623084cc3912" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivableNoncurrent_64e3cb8a-4739-4594-9fb8-b4b2b1e0e991" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesReceivableNoncurrent"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_45e00f9c-1156-4475-bc8d-08bd10a9d6ee" xlink:to="loc_us-gaap_IncomeTaxesReceivableNoncurrent_64e3cb8a-4739-4594-9fb8-b4b2b1e0e991" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_2c256855-6ffa-43c8-bd66-0a511a1b8a94" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_a4a7e056-f644-43af-a83e-9f85d753ff50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent_2c256855-6ffa-43c8-bd66-0a511a1b8a94" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_a4a7e056-f644-43af-a83e-9f85d753ff50" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_6981d201-c730-42b9-9c4b-c96951ff1b64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent_2c256855-6ffa-43c8-bd66-0a511a1b8a94" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_6981d201-c730-42b9-9c4b-c96951ff1b64" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_a8eae9e5-6af1-4018-b2d7-90cfb8114299" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_72e2b92a-1a2f-4b22-a15d-82d3cbe8e58c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_a8eae9e5-6af1-4018-b2d7-90cfb8114299" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_72e2b92a-1a2f-4b22-a15d-82d3cbe8e58c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_d3b4c9ad-6826-45e8-97f2-060e9370945a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_a8eae9e5-6af1-4018-b2d7-90cfb8114299" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_d3b4c9ad-6826-45e8-97f2-060e9370945a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_6ee78a0e-6002-41f8-8b5a-df781eac8495" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_a8eae9e5-6af1-4018-b2d7-90cfb8114299" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_6ee78a0e-6002-41f8-8b5a-df781eac8495" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_680b5e75-e1c9-496c-a8e9-110067fed7d7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_f557104c-3983-4b12-a441-6eafa4aecaab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_680b5e75-e1c9-496c-a8e9-110067fed7d7" xlink:to="loc_us-gaap_Liabilities_f557104c-3983-4b12-a441-6eafa4aecaab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_8ad5d95a-4d0d-4e85-a098-9b86cf55cad7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_680b5e75-e1c9-496c-a8e9-110067fed7d7" xlink:to="loc_us-gaap_StockholdersEquity_8ad5d95a-4d0d-4e85-a098-9b86cf55cad7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_dcab36d8-0c00-45d1-b649-57a86a7ea91b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:to="loc_us-gaap_LiabilitiesCurrent_dcab36d8-0c00-45d1-b649-57a86a7ea91b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredGainOnSaleOfProperty_7b503f9f-8dec-4984-b54e-a6376064f8cd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredGainOnSaleOfProperty"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:to="loc_us-gaap_DeferredGainOnSaleOfProperty_7b503f9f-8dec-4984-b54e-a6376064f8cd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_3a336ecb-2607-4dfd-bd3f-c542f48a56c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_3a336ecb-2607-4dfd-bd3f-c542f48a56c2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxesNoncurrent_5f0e1245-f5bc-4122-81e5-6a891195b427" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedIncomeTaxesNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:to="loc_us-gaap_AccruedIncomeTaxesNoncurrent_5f0e1245-f5bc-4122-81e5-6a891195b427" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongTermDebtNoncurrent_c9c95e60-9cf8-4d68-bda7-3ad826d9403a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLongTermDebtNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_9c50115e-03c9-4bdf-8216-dd600b1d7be0" xlink:to="loc_us-gaap_OtherLongTermDebtNoncurrent_c9c95e60-9cf8-4d68-bda7-3ad826d9403a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_47f6ff50-c547-487c-bcbb-38c98b81b9d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_47f6ff50-c547-487c-bcbb-38c98b81b9d0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_ee1cdbaf-a718-4e3d-9d80-8e30a1cc8ae6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_AccountsPayableCurrent_ee1cdbaf-a718-4e3d-9d80-8e30a1cc8ae6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_a4a6ed66-7041-4bd1-9310-819c855fc4dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_a4a6ed66-7041-4bd1-9310-819c855fc4dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_b2b86e0d-61e4-4792-9c1d-8185ea137be9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_b2b86e0d-61e4-4792-9c1d-8185ea137be9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent_be5514e3-7a8d-41c1-9543-b6562dc6d8a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedIncomeTaxesCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_AccruedIncomeTaxesCurrent_be5514e3-7a8d-41c1-9543-b6562dc6d8a0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_a4381a94-2e25-4834-95b9-4d752e540dda" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_d8840c9c-924c-498a-9b6e-e823fb56dfa4" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_a4381a94-2e25-4834-95b9-4d752e540dda" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="csgp-20201231.xsd#CONSOLIDATEDSTATEMENTSOFCASHFLOWS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_46823897-609f-4db8-8b90-b8d7bada5575" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_46823897-609f-4db8-8b90-b8d7bada5575" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_97fba486-3493-4b11-8bca-90cb4ad4eb65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_97fba486-3493-4b11-8bca-90cb4ad4eb65" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_6504338e-a929-44d3-9493-8f6e97f5a66b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_6504338e-a929-44d3-9493-8f6e97f5a66b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_ff312492-44f9-4419-8bcb-105fba6115b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_ff312492-44f9-4419-8bcb-105fba6115b1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_cdc22ddf-29b4-4df0-b3ca-3c6c7b7139aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_cdc22ddf-29b4-4df0-b3ca-3c6c7b7139aa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_ProceedsFromExerciseOfStockOptionsAndEspp_1470f388-a315-462a-be5a-8be580bfec14" xlink:href="csgp-20201231.xsd#csgp_ProceedsFromExerciseOfStockOptionsAndEspp"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_csgp_ProceedsFromExerciseOfStockOptionsAndEspp_1470f388-a315-462a-be5a-8be580bfec14" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_20e6692e-0d9e-4558-9ca6-9053c62ac5cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_94b00dc0-4be0-4028-b55f-bc0e051f75ba" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_20e6692e-0d9e-4558-9ca6-9053c62ac5cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f426c85a-abf4-4b40-a7c2-8f6459740852" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6b74d871-ec19-405c-985a-931f9e1ffc8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f426c85a-abf4-4b40-a7c2-8f6459740852" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_6b74d871-ec19-405c-985a-931f9e1ffc8a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_190216f7-02e6-444e-aab9-6a7b3eb3011d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f426c85a-abf4-4b40-a7c2-8f6459740852" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_190216f7-02e6-444e-aab9-6a7b3eb3011d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_f24dbc4e-902b-4dfe-b969-52804a6a4884" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f426c85a-abf4-4b40-a7c2-8f6459740852" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_f24dbc4e-902b-4dfe-b969-52804a6a4884" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_5b6bf50e-27e3-4456-abbc-f9fde3a4c1b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_f426c85a-abf4-4b40-a7c2-8f6459740852" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_5b6bf50e-27e3-4456-abbc-f9fde3a4c1b8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_3eb681a6-b6bb-4282-9718-295014a4546e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_3eb681a6-b6bb-4282-9718-295014a4546e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_fa138d8c-34b9-4779-838c-996a8a88ee6c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_NetIncomeLoss_fa138d8c-34b9-4779-838c-996a8a88ee6c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_8de87841-1752-420b-b337-334a146aef59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_8de87841-1752-420b-b337-334a146aef59" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_9dfbfff9-bb3f-4560-be33-c312725c9d84" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_9dfbfff9-bb3f-4560-be33-c312725c9d84" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_NonCashLeaseExpense_7ab3571c-b059-4564-a98d-997247849a69" xlink:href="csgp-20201231.xsd#csgp_NonCashLeaseExpense"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_csgp_NonCashLeaseExpense_7ab3571c-b059-4564-a98d-997247849a69" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_e26a6908-a7ce-4be7-84d5-a28ab86fedbf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_e26a6908-a7ce-4be7-84d5-a28ab86fedbf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_a1896be1-5ee3-435a-a799-ad27670b9a99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_a1896be1-5ee3-435a-a799-ad27670b9a99" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_6af33bb5-966f-438d-9f3a-0778f0c98061" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_6af33bb5-966f-438d-9f3a-0778f0c98061" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_6be572f1-92ac-469e-b116-250fbef41e86" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_6be572f1-92ac-469e-b116-250fbef41e86" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDeferredSalesCommissions_01b68265-c457-4e23-977a-cecf77be2db1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfDeferredSalesCommissions"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_AmortizationOfDeferredSalesCommissions_01b68265-c457-4e23-977a-cecf77be2db1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_e3ef3da7-2694-4f6c-98ac-43e827ad1ec5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_e3ef3da7-2694-4f6c-98ac-43e827ad1ec5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_IncreaseDecreaseInLeaseLiability_117e3bbb-98a8-458d-b0a0-df763aed8000" xlink:href="csgp-20201231.xsd#csgp_IncreaseDecreaseInLeaseLiability"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_csgp_IncreaseDecreaseInLeaseLiability_117e3bbb-98a8-458d-b0a0-df763aed8000" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_IncreaseDecreaseDeferredCommissions_b533bfb7-5f61-40b4-8ce9-9370cc2d6fe4" xlink:href="csgp-20201231.xsd#csgp_IncreaseDecreaseDeferredCommissions"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_csgp_IncreaseDecreaseDeferredCommissions_b533bfb7-5f61-40b4-8ce9-9370cc2d6fe4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_IncreaseDecreaseLeaseRightofUseandOtherAssets_0571803c-cf2f-4eb8-9989-de24e6407bdd" xlink:href="csgp-20201231.xsd#csgp_IncreaseDecreaseLeaseRightofUseandOtherAssets"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_csgp_IncreaseDecreaseLeaseRightofUseandOtherAssets_0571803c-cf2f-4eb8-9989-de24e6407bdd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_84ac5a78-5d6f-4fe4-9951-8dcf07e879fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_ShareBasedCompensation_84ac5a78-5d6f-4fe4-9951-8dcf07e879fd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_710ce895-3f6b-4bd5-ac4f-2b12883436c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_710ce895-3f6b-4bd5-ac4f-2b12883436c6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_f7be9c4f-545b-427b-bf8d-fca6614290f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b70cdeed-e391-4e7b-b561-b2801122cd2a" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable_f7be9c4f-545b-427b-bf8d-fca6614290f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a5cd18ac-9362-4129-983e-4580172bea18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_770f3891-9aa7-43a2-ba85-8f00744ab67a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a5cd18ac-9362-4129-983e-4580172bea18" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_770f3891-9aa7-43a2-ba85-8f00744ab67a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_e5219d91-d8f5-4a24-911c-7567a2edb3f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a5cd18ac-9362-4129-983e-4580172bea18" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_e5219d91-d8f5-4a24-911c-7567a2edb3f7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_7192f8e2-46b7-4b8d-a1c8-31ecbda7e20a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a5cd18ac-9362-4129-983e-4580172bea18" xlink:to="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_7192f8e2-46b7-4b8d-a1c8-31ecbda7e20a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/ORGANIZATION" xlink:type="simple" xlink:href="csgp-20201231.xsd#ORGANIZATION"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ORGANIZATION" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ORGANIZATIONDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ORGANIZATIONDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ORGANIZATIONDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESRevenueRecognitionDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESForeignCurrencyTranslationandAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESForeignCurrencyTranslationandAccumulatedOtherComprehensiveLossDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESForeignCurrencyTranslationandAccumulatedOtherComprehensiveLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_0a3642f3-88f1-4053-a5e9-88f390a80a49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_abdb065f-3095-40ae-bc21-d868ba505d02" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_0a3642f3-88f1-4053-a5e9-88f390a80a49" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax_abdb065f-3095-40ae-bc21-d868ba505d02" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_19d9486c-da07-4867-bbbc-0ab6820ecbb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_0a3642f3-88f1-4053-a5e9-88f390a80a49" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_19d9486c-da07-4867-bbbc-0ab6820ecbb8" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdvertisingCostsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdvertisingCostsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAdvertisingCostsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESStockBasedCompensationDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESStockBasedCompensationDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESStockBasedCompensationDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESCashReconciliationDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESCashReconciliationDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESCashReconciliationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_faeb691c-6a9e-476e-a616-23a4fe2aef26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_b056b46d-2a16-47f9-a3d6-c4c304db0baa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_faeb691c-6a9e-476e-a616-23a4fe2aef26" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_b056b46d-2a16-47f9-a3d6-c4c304db0baa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_e2cc2b7d-b163-4711-8b91-f9657a585d90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCash"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_faeb691c-6a9e-476e-a616-23a4fe2aef26" xlink:to="loc_us-gaap_RestrictedCash_e2cc2b7d-b163-4711-8b91-f9657a585d90" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAllowanceforCreditLossesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAllowanceforCreditLossesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESAllowanceforCreditLossesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPropertyandEquipmentDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESLongLivedAssetsIntangibleAssetsandGoodwillDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESLongLivedAssetsIntangibleAssetsandGoodwillDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESLongLivedAssetsIntangibleAssetsandGoodwillDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSDisaggregatedRevenueDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSDisaggregatedRevenueDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSDisaggregatedRevenueDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsandLiabilitiesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSContractAssetsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSCommissionsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSCommissionsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSCommissionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesCommissionsAndFees_fd96b777-b228-4d7f-bf5b-f4c634239590" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesCommissionsAndFees"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_CommissionsIncurred_b7ed78a9-3c5f-4760-88d9-9f1a99b1994c" xlink:href="csgp-20201231.xsd#csgp_CommissionsIncurred"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_SalesCommissionsAndFees_fd96b777-b228-4d7f-bf5b-f4c634239590" xlink:to="loc_csgp_CommissionsIncurred_b7ed78a9-3c5f-4760-88d9-9f1a99b1994c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_CommissionsCapitalizedintheCurrentPeriod_244d816b-6bd9-4ec9-bfae-d24809619b31" xlink:href="csgp-20201231.xsd#csgp_CommissionsCapitalizedintheCurrentPeriod"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_SalesCommissionsAndFees_fd96b777-b228-4d7f-bf5b-f4c634239590" xlink:to="loc_csgp_CommissionsCapitalizedintheCurrentPeriod_244d816b-6bd9-4ec9-bfae-d24809619b31" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDeferredSalesCommissions_0862c9fa-36be-4039-8615-a928c263f0c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfDeferredSalesCommissions"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_SalesCommissionsAndFees_fd96b777-b228-4d7f-bf5b-f4c634239590" xlink:to="loc_us-gaap_AmortizationOfDeferredSalesCommissions_0862c9fa-36be-4039-8615-a928c263f0c0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails_1" xlink:type="simple" xlink:href="csgp-20201231.xsd#REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails_1"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/REVENUEFROMCONTRACTSWITHCUSTOMERSUnsatisfiedPerformanceObligationsDetails_1" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSES" xlink:type="simple" xlink:href="csgp-20201231.xsd#ALLOWANCEFORCREDITLOSSES"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSES" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSESTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#ALLOWANCEFORCREDITLOSSESTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSESTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSESDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ALLOWANCEFORCREDITLOSSESDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ALLOWANCEFORCREDITLOSSESDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONS" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONSNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONSNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONSNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONSScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONSScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONSScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_dbdcfba8-d811-4583-bb0d-98b94016f294" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_dbdcfba8-d811-4583-bb0d-98b94016f294" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_d69f12f3-26f7-452a-a772-f39acfe110a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_d69f12f3-26f7-452a-a772-f39acfe110a6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_c68fe27f-262d-404f-9641-7d154a108b0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_c68fe27f-262d-404f-9641-7d154a108b0f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_a542afcc-054c-4570-8c86-329c92438ac0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_a542afcc-054c-4570-8c86-329c92438ac0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_cf9b3f8d-db91-469c-8c8a-ada60e9c3221" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_cf9b3f8d-db91-469c-8c8a-ada60e9c3221" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_f3c86dc8-2884-475b-8940-a6ce8d334956" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_f3c86dc8-2884-475b-8940-a6ce8d334956" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_280c6658-db49-4433-b626-e8e567de3d35" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_us-gaap_Goodwill_280c6658-db49-4433-b626-e8e567de3d35" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinanceLeaseRightOfUseAsset_607d3ceb-b94e-454d-a247-96eef14c8b3d" xlink:href="csgp-20201231.xsd#csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinanceLeaseRightOfUseAsset"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFinanceLeaseRightOfUseAsset_607d3ceb-b94e-454d-a247-96eef14c8b3d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherAssetsAndLiabilities_726cbbd4-6773-4260-9fa3-1d1b3066b21e" xlink:href="csgp-20201231.xsd#csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherAssetsAndLiabilities"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_67feb451-4718-42da-9063-5cc94d2764bb" xlink:to="loc_csgp_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedOtherAssetsAndLiabilities_726cbbd4-6773-4260-9fa3-1d1b3066b21e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONSIntangibleAssetsAcquiredDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONSIntangibleAssetsAcquiredDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONSIntangibleAssetsAcquiredDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ACQUISITIONSBusinessAcquisitionProFormaInformationDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ACQUISITIONSBusinessAcquisitionProFormaInformationDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ACQUISITIONSBusinessAcquisitionProFormaInformationDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTS" xlink:type="simple" xlink:href="csgp-20201231.xsd#INVESTMENTSANDFAIRVALUEMEASUREMENTS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#INVESTMENTSANDFAIRVALUEMEASUREMENTSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INVESTMENTSANDFAIRVALUEMEASUREMENTSNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INVESTMENTSANDFAIRVALUEMEASUREMENTSDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INVESTMENTSANDFAIRVALUEMEASUREMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_930aca65-2965-4d29-83b5-ba1b9cc6f17e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_df2d535a-7ce3-458d-854a-0333ddc4af6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_930aca65-2965-4d29-83b5-ba1b9cc6f17e" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_df2d535a-7ce3-458d-854a-0333ddc4af6f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_4acbf9c3-7f75-4088-a3e2-e1ff03e687bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_930aca65-2965-4d29-83b5-ba1b9cc6f17e" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_4acbf9c3-7f75-4088-a3e2-e1ff03e687bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_eaf33cc0-5b81-48c0-8083-e8e8f10d9f76" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_930aca65-2965-4d29-83b5-ba1b9cc6f17e" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_eaf33cc0-5b81-48c0-8083-e8e8f10d9f76" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/LEASES" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASES"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASES" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LEASESTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASESTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASESTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LEASESNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASESNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASESNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LEASESLeaseCostDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASESLeaseCostDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASESLeaseCostDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LEASESSupplementalBalanceSheetInformationRelatedtoLeasesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASESSupplementalBalanceSheetInformationRelatedtoLeasesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASESSupplementalBalanceSheetInformationRelatedtoLeasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7c01e20c-101d-48cf-8c6f-ee81ce5eb696" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_b22d7f24-0b7d-4483-8202-b413f27dfeea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7c01e20c-101d-48cf-8c6f-ee81ce5eb696" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_b22d7f24-0b7d-4483-8202-b413f27dfeea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_1b9eb802-864a-41ae-90de-cd300e2db5c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7c01e20c-101d-48cf-8c6f-ee81ce5eb696" xlink:to="loc_us-gaap_OperatingLeaseLiability_1b9eb802-864a-41ae-90de-cd300e2db5c1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_a2726d4b-0dbd-4cf3-b782-aea396b1dd63" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_652dbeeb-363b-4c98-a6d3-418d80787806" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_a2726d4b-0dbd-4cf3-b782-aea396b1dd63" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_652dbeeb-363b-4c98-a6d3-418d80787806" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_ba4a0f8b-85d1-48a6-8fb5-18f5f761f271" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeaseLiability_a2726d4b-0dbd-4cf3-b782-aea396b1dd63" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_ba4a0f8b-85d1-48a6-8fb5-18f5f761f271" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/LEASESSupplementalCashFlowInformationRelatedtoLeasesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LEASESSupplementalCashFlowInformationRelatedtoLeasesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LEASESSupplementalCashFlowInformationRelatedtoLeasesDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/PROPERTYANDEQUIPMENT" xlink:type="simple" xlink:href="csgp-20201231.xsd#PROPERTYANDEQUIPMENT"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/PROPERTYANDEQUIPMENT" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/PROPERTYANDEQUIPMENTTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#PROPERTYANDEQUIPMENTTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/PROPERTYANDEQUIPMENTTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/PROPERTYANDEQUIPMENTDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#PROPERTYANDEQUIPMENTDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/PROPERTYANDEQUIPMENTDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_74e69600-5978-44b2-8d7a-69bbf437865a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_33f0036f-4a9a-4556-911f-c9bca77d2f4a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_74e69600-5978-44b2-8d7a-69bbf437865a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_33f0036f-4a9a-4556-911f-c9bca77d2f4a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_923222fc-bfe6-40e4-9133-cf427aeb1d7e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_74e69600-5978-44b2-8d7a-69bbf437865a" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_923222fc-bfe6-40e4-9133-cf427aeb1d7e" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/GOODWILL" xlink:type="simple" xlink:href="csgp-20201231.xsd#GOODWILL"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/GOODWILL" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/GOODWILLTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#GOODWILLTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/GOODWILLTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/GOODWILLGoodwillbySegmentDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#GOODWILLGoodwillbySegmentDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/GOODWILLGoodwillbySegmentDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/GOODWILLNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#GOODWILLNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/GOODWILLNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INTANGIBLEASSETS" xlink:type="simple" xlink:href="csgp-20201231.xsd#INTANGIBLEASSETS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INTANGIBLEASSETS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INTANGIBLEASSETSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#INTANGIBLEASSETSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INTANGIBLEASSETSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INTANGIBLEASSETSDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INTANGIBLEASSETSDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INTANGIBLEASSETSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_53834090-f4cc-43ed-825e-5be92657e618" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_864b93e9-51d9-43fd-b962-14c4c74d7cb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_53834090-f4cc-43ed-825e-5be92657e618" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_864b93e9-51d9-43fd-b962-14c4c74d7cb6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_e6efb0e1-1749-4ee9-8a19-2fce61031f1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_53834090-f4cc-43ed-825e-5be92657e618" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_e6efb0e1-1749-4ee9-8a19-2fce61031f1d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/LONGTERMDEBT" xlink:type="simple" xlink:href="csgp-20201231.xsd#LONGTERMDEBT"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LONGTERMDEBT" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LONGTERMDEBTTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#LONGTERMDEBTTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LONGTERMDEBTTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LONGTERMDEBTScheduleofDebtDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LONGTERMDEBTScheduleofDebtDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LONGTERMDEBTScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_97b6158c-5886-404d-9c82-f5dfc674b264" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_f2c13ed7-1c72-4bf6-99ae-eb98e7854f59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_97b6158c-5886-404d-9c82-f5dfc674b264" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_f2c13ed7-1c72-4bf6-99ae-eb98e7854f59" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_00d821d3-5e54-4e99-81f6-352b85271c89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_97b6158c-5886-404d-9c82-f5dfc674b264" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_00d821d3-5e54-4e99-81f6-352b85271c89" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/LONGTERMDEBTNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LONGTERMDEBTNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LONGTERMDEBTNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/LONGTERMDEBTInterestDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#LONGTERMDEBTInterestDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/LONGTERMDEBTInterestDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXES" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXES"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXES" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESComponentsforProvisionforIncomeTaxesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESComponentsforProvisionforIncomeTaxesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESComponentsforProvisionforIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_5e6a6ad9-82b5-48c2-9dce-7e2447420e33" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_148ba20b-9076-4cfa-aac7-4bafefdc1d9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_5e6a6ad9-82b5-48c2-9dce-7e2447420e33" xlink:to="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_148ba20b-9076-4cfa-aac7-4bafefdc1d9e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOtherTaxExpenseBenefit_feef5490-508a-469b-ae78-2ad41a2978ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredOtherTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_5e6a6ad9-82b5-48c2-9dce-7e2447420e33" xlink:to="loc_us-gaap_DeferredOtherTaxExpenseBenefit_feef5490-508a-469b-ae78-2ad41a2978ad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_be5042ed-cb22-45a3-95a7-437718ea872a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit_ddd7bf4b-c71c-4f59-89d8-9420bb41f14d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_be5042ed-cb22-45a3-95a7-437718ea872a" xlink:to="loc_us-gaap_CurrentFederalTaxExpenseBenefit_ddd7bf4b-c71c-4f59-89d8-9420bb41f14d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_a414e396-d038-4fa2-a49a-df37e86e4d49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_be5042ed-cb22-45a3-95a7-437718ea872a" xlink:to="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_a414e396-d038-4fa2-a49a-df37e86e4d49" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_dfeaa8f7-2a2b-4f94-b975-f546cec82855" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_be5042ed-cb22-45a3-95a7-437718ea872a" xlink:to="loc_us-gaap_CurrentForeignTaxExpenseBenefit_dfeaa8f7-2a2b-4f94-b975-f546cec82855" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3b9ae6af-c41f-454a-80c5-843aaae1ea66" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredOtherTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_a7eb8d5d-45e1-42d5-be0a-b18648758c39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3b9ae6af-c41f-454a-80c5-843aaae1ea66" xlink:to="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_a7eb8d5d-45e1-42d5-be0a-b18648758c39" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_880a1567-3f20-427d-9f3c-016ccc009374" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3b9ae6af-c41f-454a-80c5-843aaae1ea66" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_880a1567-3f20-427d-9f3c-016ccc009374" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_5e97898f-f622-43e6-9300-e636283951b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredOtherTaxExpenseBenefit_3b9ae6af-c41f-454a-80c5-843aaae1ea66" xlink:to="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_5e97898f-f622-43e6-9300-e636283951b2" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESComponentsofDeferredTaxAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESComponentsofDeferredTaxAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESComponentsofDeferredTaxAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_14514588-8a88-44e5-beca-c29a17d05d89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_14514588-8a88-44e5-beca-c29a17d05d89" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_b09e058d-84f3-43ed-8bf8-2b3adff82972" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_b09e058d-84f3-43ed-8bf8-2b3adff82972" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_f481fe7f-d527-4699-ac26-2b2d4a34c43a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_f481fe7f-d527-4699-ac26-2b2d4a34c43a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_b4101138-93c7-4080-ba1a-0ceb639a52df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_b4101138-93c7-4080-ba1a-0ceb639a52df" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_5a659c91-5714-4a6d-99f5-51683eaa8ca5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsReserves_5a659c91-5714-4a6d-99f5-51683eaa8ca5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_a70c66e3-7e1f-43e5-a927-8ec3b3a652f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_a70c66e3-7e1f-43e5-a927-8ec3b3a652f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_DeferredTaxAssetsLeaseLiabilities_395e628e-ca21-4683-b9fe-c82f10f13095" xlink:href="csgp-20201231.xsd#csgp_DeferredTaxAssetsLeaseLiabilities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_csgp_DeferredTaxAssetsLeaseLiabilities_395e628e-ca21-4683-b9fe-c82f10f13095" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_DeferredTaxAssetsAccruedTransactionFees_69ca35f1-541a-49f3-aa10-5a06c7c66212" xlink:href="csgp-20201231.xsd#csgp_DeferredTaxAssetsAccruedTransactionFees"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsGross_e42144c9-cdfd-46a7-bcb6-ac282a46e04f" xlink:to="loc_csgp_DeferredTaxAssetsAccruedTransactionFees_69ca35f1-541a-49f3-aa10-5a06c7c66212" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_f50bae82-14a2-4a4b-b72e-def194d62bcb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPrepaidExpenses"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_f50bae82-14a2-4a4b-b72e-def194d62bcb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_5b11d3af-b6c2-429d-bbda-1c8a97e97bbd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_5b11d3af-b6c2-429d-bbda-1c8a97e97bbd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_6eb0025b-4c32-4b88-b7a4-c975bdac9d4f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_6eb0025b-4c32-4b88-b7a4-c975bdac9d4f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_DeferredTaxLiabilitiesAccruedCommissions_d195f952-db23-4262-9a1a-c1b38b048b30" xlink:href="csgp-20201231.xsd#csgp_DeferredTaxLiabilitiesAccruedCommissions"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:to="loc_csgp_DeferredTaxLiabilitiesAccruedCommissions_d195f952-db23-4262-9a1a-c1b38b048b30" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_DeferredTaxLiabilitiesLeaseRightofUseAssets_3f913303-1b28-4578-8314-0d23f090e643" xlink:href="csgp-20201231.xsd#csgp_DeferredTaxLiabilitiesLeaseRightofUseAssets"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities_2a62193f-f3ec-4629-9112-d626b8082895" xlink:to="loc_csgp_DeferredTaxLiabilitiesLeaseRightofUseAssets_3f913303-1b28-4578-8314-0d23f090e643" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities_339241b8-88a1-459b-9f46-10ab2344bebc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxLiabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_784baa8a-ee57-4d10-b8ae-9367cffb58ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_339241b8-88a1-459b-9f46-10ab2344bebc" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_784baa8a-ee57-4d10-b8ae-9367cffb58ee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_7a1d8824-4f01-47bc-b8a7-64335cde3b91" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxLiabilities_339241b8-88a1-459b-9f46-10ab2344bebc" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_7a1d8824-4f01-47bc-b8a7-64335cde3b91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_7fac56af-7334-479c-aa35-4932b6cc0c7e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_fe86958a-55bf-45e4-9a33-9faf2e38a034" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_7fac56af-7334-479c-aa35-4932b6cc0c7e" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_fe86958a-55bf-45e4-9a33-9faf2e38a034" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_fd892c8f-f85f-4550-98e5-c8a305be9a36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredTaxAssetsNet_7fac56af-7334-479c-aa35-4932b6cc0c7e" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_fd892c8f-f85f-4550-98e5-c8a305be9a36" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESReconciliationofProvisionforIncomeTaxesDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESReconciliationofProvisionforIncomeTaxesDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESReconciliationofProvisionforIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_EffectiveIncomeTaxRateReconciliationChangeInTaxReservesAmount_508184e7-67c9-41db-bca7-075fec3d703a" xlink:href="csgp-20201231.xsd#csgp_EffectiveIncomeTaxRateReconciliationChangeInTaxReservesAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_csgp_EffectiveIncomeTaxRateReconciliationChangeInTaxReservesAmount_508184e7-67c9-41db-bca7-075fec3d703a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseCompensationAmount_19ebbc10-308b-4427-b990-ca8930827312" xlink:href="csgp-20201231.xsd#csgp_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseCompensationAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_csgp_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseCompensationAmount_19ebbc10-308b-4427-b990-ca8930827312" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_52f8bc83-9c1f-4a05-8fd7-7612fbb2151b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsResearch"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsResearch_52f8bc83-9c1f-4a05-8fd7-7612fbb2151b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_7f7f01f4-67d0-4a75-ae6f-7276c5f63d2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_7f7f01f4-67d0-4a75-ae6f-7276c5f63d2b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_5ca66e84-3666-48a8-ad64-a605ecce0bc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_5ca66e84-3666-48a8-ad64-a605ecce0bc9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_EffectiveIncomeTaxRateReconciliationExcessTaxBenefitAmount_626b6c0e-9ad7-4b62-b3a5-1fe2a0e955ca" xlink:href="csgp-20201231.xsd#csgp_EffectiveIncomeTaxRateReconciliationExcessTaxBenefitAmount"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_csgp_EffectiveIncomeTaxRateReconciliationExcessTaxBenefitAmount_626b6c0e-9ad7-4b62-b3a5-1fe2a0e955ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_aeccfc81-3132-4603-bc62-944ceb9900e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_aeccfc81-3132-4603-bc62-944ceb9900e8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_d0e002d5-7fb2-4c51-9536-dce2a2b72a21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit_efa24c95-c0b6-4b59-8343-8827ca736368" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_d0e002d5-7fb2-4c51-9536-dce2a2b72a21" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/INCOMETAXESUnrecognizedTaxBenefitsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#INCOMETAXESUnrecognizedTaxBenefitsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/INCOMETAXESUnrecognizedTaxBenefitsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIES" xlink:type="simple" xlink:href="csgp-20201231.xsd#COMMITMENTSANDCONTINGENCIES"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIES" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#COMMITMENTSANDCONTINGENCIESTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#COMMITMENTSANDCONTINGENCIESDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPayments"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsYearThree_cbbccff5-02f5-42b7-a9ab-f276ea0d67d7" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsYearThree"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsYearThree_cbbccff5-02f5-42b7-a9ab-f276ea0d67d7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsYearFive_a7e715c7-d2df-4d1c-9b63-532809bea058" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsYearFive"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsYearFive_a7e715c7-d2df-4d1c-9b63-532809bea058" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsYearTwo_921f9a12-3037-4d33-9496-0a61cb3f2541" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsYearTwo"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsYearTwo_921f9a12-3037-4d33-9496-0a61cb3f2541" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsYearFour_2abe1070-822b-45c6-a64b-3e0656c1eb8a" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsYearFour_2abe1070-822b-45c6-a64b-3e0656c1eb8a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsYearOne_19351e02-971f-4d5c-a478-b8ae0320b2ab" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsYearOne"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsYearOne_19351e02-971f-4d5c-a478-b8ae0320b2ab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_csgp_LongTermDebtMaturityInterestPaymentsAfterYearFive_7b6ce400-e03a-4cb0-84ca-922116a70a58" xlink:href="csgp-20201231.xsd#csgp_LongTermDebtMaturityInterestPaymentsAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_csgp_LongTermDebtMaturityInterestPayments_1f86e19b-cdbc-412a-99e6-f923598427e6" xlink:to="loc_csgp_LongTermDebtMaturityInterestPaymentsAfterYearFive_7b6ce400-e03a-4cb0-84ca-922116a70a58" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_b3c408e2-752f-4bb5-b5d8-5da7ed77407f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_b3c408e2-752f-4bb5-b5d8-5da7ed77407f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_952174cd-f482-47a1-a80b-b657e2bcf70d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_952174cd-f482-47a1-a80b-b657e2bcf70d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_e86e7b18-563b-41b7-a27e-57130653f6dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_e86e7b18-563b-41b7-a27e-57130653f6dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_e6e28aab-7084-4784-82c3-a02ffc9b0c5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_e6e28aab-7084-4784-82c3-a02ffc9b0c5c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_f2f2a35d-8c01-4712-a714-047e9c8acd85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_f2f2a35d-8c01-4712-a714-047e9c8acd85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_aa5f78a2-528f-4988-8b71-49f630dc10d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_7f512285-4624-4f0f-8fa6-c56e4c708bff" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_aa5f78a2-528f-4988-8b71-49f630dc10d5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_b9ad1d89-f8b0-48c1-b987-fcc5f4baf703" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_b9ad1d89-f8b0-48c1-b987-fcc5f4baf703" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_1b2b391e-8510-4ef8-915f-48f4ca4f9125" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_1b2b391e-8510-4ef8-915f-48f4ca4f9125" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_8e7cc72f-f40d-4678-b4d2-8a03b1cda369" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_8e7cc72f-f40d-4678-b4d2-8a03b1cda369" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_bbfe69b5-f062-418d-aafa-784460db3a60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_bbfe69b5-f062-418d-aafa-784460db3a60" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_4d0b4e6a-005b-4d5c-8856-08663495f18f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_4d0b4e6a-005b-4d5c-8856-08663495f18f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_4fa5daae-4881-4cb0-8116-69ede5cf71fd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_185e8e5c-b505-4759-bfb6-03360512156c" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_4fa5daae-4881-4cb0-8116-69ede5cf71fd" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#COMMITMENTSANDCONTINGENCIESNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/COMMITMENTSANDCONTINGENCIESNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTING" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTING"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTING" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTINGTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTINGTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTINGTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTINGNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTINGNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTINGNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTINGEBITDADetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTINGEBITDADetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTINGEBITDADetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTINGReconciliationofNetIncomeLosstoEBITDADetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTINGReconciliationofNetIncomeLosstoEBITDADetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTINGReconciliationofNetIncomeLosstoEBITDADetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SEGMENTREPORTINGSummarizedInformationDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SEGMENTREPORTINGSummarizedInformationDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SEGMENTREPORTINGSummarizedInformationDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/STOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="csgp-20201231.xsd#STOCKHOLDERSEQUITY"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/STOCKHOLDERSEQUITY" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/STOCKHOLDERSEQUITYDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#STOCKHOLDERSEQUITYDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/STOCKHOLDERSEQUITYDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/NETINCOMEPERSHARE" xlink:type="simple" xlink:href="csgp-20201231.xsd#NETINCOMEPERSHARE"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/NETINCOMEPERSHARE" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/NETINCOMEPERSHARETables" xlink:type="simple" xlink:href="csgp-20201231.xsd#NETINCOMEPERSHARETables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/NETINCOMEPERSHARETables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/NETINCOMEPERSHAREDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#NETINCOMEPERSHAREDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/NETINCOMEPERSHAREDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_095fcf80-3c1d-49d0-9b1a-b7ac8359220a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_18b64f6c-237a-4797-9b5e-32c7d24c7961" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_095fcf80-3c1d-49d0-9b1a-b7ac8359220a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_18b64f6c-237a-4797-9b5e-32c7d24c7961" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_7559a8af-b0d7-4694-88cb-253ff64011f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_095fcf80-3c1d-49d0-9b1a-b7ac8359220a" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_7559a8af-b0d7-4694-88cb-253ff64011f3" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANS" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSStockIncentivePlansNarrativeDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSStockIncentivePlansNarrativeDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSStockIncentivePlansNarrativeDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSStockOptionActivityDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSStockOptionActivityDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSStockOptionActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSAssumptionsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSAssumptionsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSAssumptionsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSInformationRegardingStockOptionsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSInformationRegardingStockOptionsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSInformationRegardingStockOptionsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSRestrictiveStockAwardActivityDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSRestrictiveStockAwardActivityDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSRestrictiveStockAwardActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSRestrictiveStockUnitsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSRestrictiveStockUnitsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSRestrictiveStockUnitsDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSMSUandDSUActivityDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSMSUandDSUActivityDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSMSUandDSUActivityDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/EMPLOYEEBENEFITPLANSEmployee401kPlanEmployeePensionPlanRegisteredRetirementSavingsPlanandEmployeeStockPurchasePlanDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#EMPLOYEEBENEFITPLANSEmployee401kPlanEmployeePensionPlanRegisteredRetirementSavingsPlanandEmployeeStockPurchasePlanDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/EMPLOYEEBENEFITPLANSEmployee401kPlanEmployeePensionPlanRegisteredRetirementSavingsPlanandEmployeeStockPurchasePlanDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONS" xlink:type="simple" xlink:href="csgp-20201231.xsd#QUARTERLYRESULTSOFOPERATIONS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONSTables" xlink:type="simple" xlink:href="csgp-20201231.xsd#QUARTERLYRESULTSOFOPERATIONSTables"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONSTables" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONSDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#QUARTERLYRESULTSOFOPERATIONSDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/QUARTERLYRESULTSOFOPERATIONSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_33631072-ab7f-4f34-8c63-7bc7cabc61dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_797ce34e-0411-45c5-a902-a62e8819963f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_33631072-ab7f-4f34-8c63-7bc7cabc61dc" xlink:to="loc_us-gaap_GrossProfit_797ce34e-0411-45c5-a902-a62e8819963f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_c9995564-46b2-446c-952b-e044836b58b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_33631072-ab7f-4f34-8c63-7bc7cabc61dc" xlink:to="loc_us-gaap_OperatingExpenses_c9995564-46b2-446c-952b-e044836b58b6" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.costar.com/role/SUBSEQUENTEVENTS" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUBSEQUENTEVENTS"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUBSEQUENTEVENTS" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/SUBSEQUENTEVENTSDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#SUBSEQUENTEVENTSDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/SUBSEQUENTEVENTSDetails" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ScheduleIIValuationandQualifyingAccounts" xlink:type="simple" xlink:href="csgp-20201231.xsd#ScheduleIIValuationandQualifyingAccounts"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ScheduleIIValuationandQualifyingAccounts" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.costar.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="simple" xlink:href="csgp-20201231.xsd#ScheduleIIValuationandQualifyingAccountsDetails"/>
  <link:calculationLink xlink:role="http://www.costar.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="extended"/>
</link:linkbase>
