<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  11.0.0.3 -->
<!--Based on XBRL 2.1-->
<!--Created on: 7/30/2025 12:35:39 PM-->
<!--Modified on: 7/30/2025 12:35:39 PM-->
<link:linkbase 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" xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance">
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#StatementCondensedConsolidatedBalanceSheets" roleURI="http://www.pcconnection.com/role/StatementCondensedConsolidatedBalanceSheets" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#StatementCondensedConsolidatedStatementsOfIncome" roleURI="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfIncome" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#StatementCondensedConsolidatedStatementsOfOtherComprehensiveIncome" roleURI="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfOtherComprehensiveIncome" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#StatementCondensedConsolidatedStatementsOfCashFlows" roleURI="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfCashFlows" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureFairValueMeasurementsAvailableForSaleInvestmentsDetails" roleURI="http://www.pcconnection.com/role/DisclosureFairValueMeasurementsAvailableForSaleInvestmentsDetails" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureEarningsPerShareDetails" roleURI="http://www.pcconnection.com/role/DisclosureEarningsPerShareDetails" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureLeasesFutureLeasePaymentsDetailsCalc2" roleURI="http://www.pcconnection.com/role/DisclosureLeasesFutureLeasePaymentsDetailsCalc2" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureLeasesLeaseCostAndOtherInformationDetails" roleURI="http://www.pcconnection.com/role/DisclosureLeasesLeaseCostAndOtherInformationDetails" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureLeasesFutureLeasePaymentsDetails" roleURI="http://www.pcconnection.com/role/DisclosureLeasesFutureLeasePaymentsDetails" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureAccumulatedOtherComprehensiveLossIncomeDetails" roleURI="http://www.pcconnection.com/role/DisclosureAccumulatedOtherComprehensiveLossIncomeDetails" />
  <link:roleRef xlink:type="simple" xlink:href="cnxn-20250630.xsd#DisclosureSegmentInformationSegmentInformationApplicableToReportableOperatingSegmentsDetails" roleURI="http://www.pcconnection.com/role/DisclosureSegmentInformationSegmentInformationApplicableToReportableOperatingSegmentsDetails" />
  <link:arcroleRef arcroleURI="https://xbrl.org/2023/arcrole/summation-item" xlink:type="simple" xlink:href="https://www.xbrl.org/2023/calculation-1.1.xsd#summation-item" />
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/StatementCondensedConsolidatedBalanceSheets" xlink:type="extended" xlink:title="995200100 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets" xlink:label="Assets" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent_638894757381931288" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_AssetsCurrent_638894757381931288" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue_638894757381931288" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent_638894757381931288" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue_638894757381931288" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestments" xlink:label="us-gaap_ShortTermInvestments_638894757381931288" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent_638894757381931288" xlink:to="us-gaap_ShortTermInvestments_638894757381931288" order="2" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="us-gaap_AccountsReceivableNetCurrent_638894757381931288" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent_638894757381931288" xlink:to="us-gaap_AccountsReceivableNetCurrent_638894757381931288" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent_638894757381931288" xlink:to="us-gaap_InventoryNet_638894757381941268" order="4" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent_638894757381931288" xlink:to="us-gaap_PrepaidExpenseAndOtherAssetsCurrent_638894757381941268" order="5" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset_638894757381941268" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_PropertyPlantAndEquipmentNet_638894757381941268" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_Goodwill_638894757381941268" order="4" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_638894757381941268" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_638894757381941268" order="5" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent_638894757381951258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="Assets" xlink:to="us-gaap_OtherAssetsNoncurrent_638894757381951258" order="6" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="LiabilitiesAndStockholdersEquity" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities_638894757381951258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_Liabilities_638894757381951258" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent_638894757381951258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_Liabilities_638894757381951258" xlink:to="us-gaap_LiabilitiesCurrent_638894757381951258" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent" xlink:label="us-gaap_AccountsPayableCurrent_638894757381951258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent_638894757381951258" xlink:to="us-gaap_AccountsPayableCurrent_638894757381951258" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilities" xlink:label="us-gaap_AccruedLiabilitiesAndOtherLiabilities_638894757381951258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent_638894757381951258" xlink:to="us-gaap_AccruedLiabilitiesAndOtherLiabilities_638894757381951258" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="us-gaap_EmployeeRelatedLiabilitiesCurrent_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent_638894757381951258" xlink:to="us-gaap_EmployeeRelatedLiabilitiesCurrent_638894757381961267" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_Liabilities_638894757381951258" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent_638894757381961267" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:label="us-gaap_DeferredIncomeTaxLiabilitiesNet_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_Liabilities_638894757381951258" xlink:to="us-gaap_DeferredIncomeTaxLiabilitiesNet_638894757381961267" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_Liabilities_638894757381951258" xlink:to="us-gaap_OtherLiabilitiesNoncurrent_638894757381961267" order="4" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_StockholdersEquity_638894757381961267" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue_638894757381961267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity_638894757381961267" xlink:to="us-gaap_CommonStockValue_638894757381961267" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_638894757381971258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity_638894757381961267" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock_638894757381971258" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_638894757381971258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity_638894757381961267" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_638894757381971258" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_638894757381971258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity_638894757381961267" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_638894757381971258" order="4" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonValue" xlink:label="us-gaap_TreasuryStockCommonValue_638894757381971258" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity_638894757381961267" xlink:to="us-gaap_TreasuryStockCommonValue_638894757381971258" order="5" use="optional" weight="-1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfIncome" xlink:type="extended" xlink:title="995200200 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="NetIncomeLoss" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="NetIncomeLoss" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_638894757381981261" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_638894757381981261" xlink:to="us-gaap_OperatingIncomeLoss_638894757381981261" order="1" use="optional" weight="1" priority="3" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit" xlink:label="us-gaap_GrossProfit_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss_638894757381981261" xlink:to="us-gaap_GrossProfit_638894757381981261" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_GrossProfit_638894757381981261" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_638894757381981261" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="us-gaap_CostOfGoodsAndServicesSold_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_GrossProfit_638894757381981261" xlink:to="us-gaap_CostOfGoodsAndServicesSold_638894757381981261" order="2" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss_638894757381981261" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_638894757381981261" order="2" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeveranceCosts1" xlink:label="us-gaap_SeveranceCosts1_638894757381981261" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss_638894757381981261" xlink:to="us-gaap_SeveranceCosts1_638894757381981261" order="3" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="us-gaap_InterestIncomeExpenseNonoperatingNet_638894757381991265" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_638894757381981261" xlink:to="us-gaap_InterestIncomeExpenseNonoperatingNet_638894757381991265" order="2" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncome" xlink:label="us-gaap_OtherNonoperatingIncome_638894757381991265" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_638894757381981261" xlink:to="us-gaap_OtherNonoperatingIncome_638894757381991265" order="3" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit_638894757381991265" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="NetIncomeLoss" xlink:to="us-gaap_IncomeTaxExpenseBenefit_638894757381991265" order="2" use="optional" weight="-1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfOtherComprehensiveIncome" xlink:type="extended" xlink:title="995200300 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OTHER COMPREHENSIVE INCOME">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_638894757381991265" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_NetIncomeLoss_638894757381991265" order="1" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent" xlink:label="us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_638894757381991265" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_638894757381991265" order="2" use="optional" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/StatementCondensedConsolidatedStatementsOfCashFlows" xlink:type="extended" xlink:title="995200500 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" order="1" use="optional" weight="1" priority="5" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss_638894757382001267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_ProfitLoss_638894757382001267" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAndAmortization" xlink:label="us-gaap_DepreciationAndAmortization_638894757382001267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_DepreciationAndAmortization_638894757382001267" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_638894757382001267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_ProvisionForDoubtfulAccounts_638894757382001267" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="cnxn-20250630.xsd#cnxn_DeferredIncomeTaxExpenseBenefitAdjusted" xlink:label="cnxn_DeferredIncomeTaxExpenseBenefitAdjusted_638894757382001267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="cnxn_DeferredIncomeTaxExpenseBenefitAdjusted_638894757382001267" order="4" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_ShareBasedCompensation_638894757382011267" order="5" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeAmortizationOfDiscount" xlink:label="us-gaap_InvestmentIncomeAmortizationOfDiscount_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_InvestmentIncomeAmortizationOfDiscount_638894757382011267" order="6" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainOnSaleOfInvestments" xlink:label="us-gaap_GainOnSaleOfInvestments_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_GainOnSaleOfInvestments_638894757382011267" order="7" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment" xlink:label="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_GainLossOnSaleOfPropertyPlantEquipment_638894757382011267" order="8" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivable_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivable_638894757382011267" order="9" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="us-gaap_IncreaseDecreaseInInventories_638894757382011267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInInventories_638894757382011267" order="10" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_638894757382021277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_638894757382021277" order="11" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_638894757382021277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_638894757382021277" order="12" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_638894757382021277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable_638894757382021277" order="13" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities_638894757382021277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities_638894757382001267" xlink:to="us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities_638894757382021277" order="14" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" order="2" use="optional" weight="1" priority="5" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireShortTermInvestments" xlink:label="us-gaap_PaymentsToAcquireShortTermInvestments_638894757382031375" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" xlink:to="us-gaap_PaymentsToAcquireShortTermInvestments_638894757382031375" order="1" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfShortTermInvestments" xlink:label="us-gaap_ProceedsFromSaleOfShortTermInvestments_638894757382031375" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" xlink:to="us-gaap_ProceedsFromSaleOfShortTermInvestments_638894757382031375" order="2" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments" xlink:label="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments_638894757382031375" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" xlink:to="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments_638894757382031375" order="3" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_638894757382031375" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities_638894757382021277" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_638894757382031375" order="4" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" order="3" use="optional" weight="1" priority="5" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="us-gaap_ProceedsFromLinesOfCredit_638894757382041264" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_ProceedsFromLinesOfCredit_638894757382041264" order="1" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="us-gaap_RepaymentsOfLinesOfCredit_638894757382041264" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_RepaymentsOfLinesOfCredit_638894757382041264" order="2" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividends" xlink:label="us-gaap_PaymentsOfDividends_638894757382041264" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_PaymentsOfDividends_638894757382041264" order="3" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="us-gaap_ProceedsFromStockPlans_638894757382041264" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_ProceedsFromStockPlans_638894757382041264" order="4" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_638894757382051277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_638894757382051277" order="5" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_638894757382051277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="us-gaap_PaymentsForRepurchaseOfCommonStock_638894757382051277" order="6" use="optional" weight="-1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="cnxn-20250630.xsd#cnxn_PaymentExerciseTaxRepurchaseOfCommonStock" xlink:label="cnxn_PaymentExerciseTaxRepurchaseOfCommonStock_638894757382051277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities_638894757382031375" xlink:to="cnxn_PaymentExerciseTaxRepurchaseOfCommonStock_638894757382051277" order="7" use="optional" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureFairValueMeasurementsAvailableForSaleInvestmentsDetails" xlink:type="extended" xlink:title="99940301 - Disclosure - Fair Value Measurements - Available-for-Sale Investments (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_638894757382051277" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:to="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_638894757382051277" order="1" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_638894757382061272" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:to="us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_638894757382061272" order="2" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecurities_638894757382061272" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:to="us-gaap_AvailableForSaleSecuritiesDebtSecurities_638894757382061272" order="3" use="optional" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureEarningsPerShareDetails" xlink:type="extended" xlink:title="99940401 - Disclosure - Earnings Per Share (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="WeightedAverageNumberOfDilutedSharesOutstanding" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_638894757382161280" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_638894757382161280" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_638894757382161280" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_638894757382161280" order="2" use="optional" weight="1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureLeasesFutureLeasePaymentsDetailsCalc2" xlink:type="extended" xlink:title="40402 - Disclosure - LEASES - Future Lease Payments (Details) CALC 2">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability_638894757382161280" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_OperatingLeaseLiability_638894757382161280" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_638894757382161280" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_638894757382161280" order="2" use="optional" weight="1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureLeasesLeaseCostAndOtherInformationDetails" xlink:type="extended" xlink:title="99940501 - Disclosure - Leases - Lease Cost and Other Information (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseCost" xlink:label="us-gaap_LeaseCost" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseCost" xlink:label="us-gaap_OperatingLeaseCost_638894757382171273" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_OperatingLeaseCost_638894757382171273" order="1" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermLeaseCost" xlink:label="us-gaap_ShortTermLeaseCost_638894757382171273" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_ShortTermLeaseCost_638894757382171273" order="2" use="optional" weight="1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureLeasesFutureLeasePaymentsDetails" xlink:type="extended" xlink:title="99940502 - Disclosure - Leases - Future Lease Payments (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_638894757382171273" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_638894757382171273" order="1" use="optional" weight="1" priority="3" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_638894757382171273" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_638894757382171273" order="2" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_638894757382171273" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_638894757382171273" order="3" use="optional" weight="1" priority="2" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_638894757382181267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_638894757382181267" order="4" use="optional" weight="1" priority="2" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureAccumulatedOtherComprehensiveLossIncomeDetails" xlink:type="extended" xlink:title="99940601 - Disclosure - Accumulated Other Comprehensive (Loss) Income (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_638894757382181267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_638894757382181267" order="1" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax" xlink:label="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_638894757382181267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_638894757382181267" order="2" use="optional" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.pcconnection.com/role/DisclosureSegmentInformationSegmentInformationApplicableToReportableOperatingSegmentsDetails" xlink:type="extended" xlink:title="99940701 - Disclosure - Segment Information - Segment Information Applicable to Reportable Operating Segments (Details)">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_638894757382181267" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_638894757382181267" order="1" use="optional" weight="1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="us-gaap_CostOfGoodsAndServicesSold_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_CostOfGoodsAndServicesSold_638894757382191266" order="2" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="us-gaap_LaborAndRelatedExpense_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_LaborAndRelatedExpense_638894757382191266" order="3" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketingExpense" xlink:label="us-gaap_MarketingExpense_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_MarketingExpense_638894757382191266" order="4" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="cnxn-20250630.xsd#cnxn_AllocatedCorporateOverheadCosts" xlink:label="cnxn_AllocatedCorporateOverheadCosts_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="cnxn_AllocatedCorporateOverheadCosts_638894757382191266" order="5" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAndAmortization" xlink:label="us-gaap_DepreciationAndAmortization_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_DepreciationAndAmortization_638894757382191266" order="6" use="optional" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount" xlink:label="us-gaap_SegmentReportingOtherItemAmount_638894757382191266" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_SegmentReportingOtherItemAmount_638894757382191266" order="7" use="optional" weight="-1" />
  </link:calculationLink>
</link:linkbase>
