<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.5c -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#Cover" roleURI="http://focusuniversal.com/role/Cover" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#CondensedConsolidatedBalanceSheets" roleURI="http://focusuniversal.com/role/CondensedConsolidatedBalanceSheets" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#CondensedConsolidatedBalanceSheetsParenthetical" roleURI="http://focusuniversal.com/role/CondensedConsolidatedBalanceSheetsParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" roleURI="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#CondensedConsolidatedStatementsOfRedeemablePreferredStockAndStockholdersEquity" roleURI="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfRedeemablePreferredStockAndStockholdersEquity" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#CondensedConsolidatedStatementsOfCashFlows" roleURI="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfCashFlows" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#OrganizationAndOperations" roleURI="http://focusuniversal.com/role/OrganizationAndOperations" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPolicies" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#RecentAccountingPronouncements" roleURI="http://focusuniversal.com/role/RecentAccountingPronouncements" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#Inventory" roleURI="http://focusuniversal.com/role/Inventory" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#PropertyAndEquipment" roleURI="http://focusuniversal.com/role/PropertyAndEquipment" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#RentalOperations" roleURI="http://focusuniversal.com/role/RentalOperations" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SeriesBRedeemablePreferredStockTemporaryEquity" roleURI="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquity" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#Leases" roleURI="http://focusuniversal.com/role/Leases" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#BankLoan" roleURI="http://focusuniversal.com/role/BankLoan" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#StockholdersEquity" roleURI="http://focusuniversal.com/role/StockholdersEquity" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SegmentReporting" roleURI="http://focusuniversal.com/role/SegmentReporting" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#Contingencies" roleURI="http://focusuniversal.com/role/Contingencies" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SubsequentEvents" roleURI="http://focusuniversal.com/role/SubsequentEvents" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesPolicies" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesTables" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#InventoryTables" roleURI="http://focusuniversal.com/role/InventoryTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#PropertyAndEquipmentTables" roleURI="http://focusuniversal.com/role/PropertyAndEquipmentTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#RentalOperationsTables" roleURI="http://focusuniversal.com/role/RentalOperationsTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SeriesBRedeemablePreferredStockTemporaryEquityTables" roleURI="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#LeasesTables" roleURI="http://focusuniversal.com/role/LeasesTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#BankLoanTables" roleURI="http://focusuniversal.com/role/BankLoanTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#StockholdersEquityTables" roleURI="http://focusuniversal.com/role/StockholdersEquityTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SegmentReportingTables" roleURI="http://focusuniversal.com/role/SegmentReportingTables" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#OrganizationAndOperationsDetailsNarrative" roleURI="http://focusuniversal.com/role/OrganizationAndOperationsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesDetails-fairValueRecurringBasis" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-fairValueRecurringBasis" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesDetails-AntidilutiveShares" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-AntidilutiveShares" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesDetails-ForeignCurrencyTranslation" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-ForeignCurrencyTranslation" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SummaryOfSignificantAccountingPoliciesDetailsNarrative" roleURI="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#InventoryDetails-Inventory" roleURI="http://focusuniversal.com/role/InventoryDetails-Inventory" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#PropertyAndEquipmentDetails-PropertyAndEquipment" roleURI="http://focusuniversal.com/role/PropertyAndEquipmentDetails-PropertyAndEquipment" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#PropertyAndEquipmentDetailsNarrative" roleURI="http://focusuniversal.com/role/PropertyAndEquipmentDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#RentalOperationsDetails-FutureRents" roleURI="http://focusuniversal.com/role/RentalOperationsDetails-FutureRents" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#RentalOperationsDetailsNarrative" roleURI="http://focusuniversal.com/role/RentalOperationsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SeriesBRedeemablePreferredStockTemporaryEquityDetails-BalanceSheetReconciled" roleURI="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityDetails-BalanceSheetReconciled" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SeriesBRedeemablePreferredStockTemporaryEquityDetailsNarrative" roleURI="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#LeasesDetails-OperatingLeaseRightOfUseAssetAndLiabilities" roleURI="http://focusuniversal.com/role/LeasesDetails-OperatingLeaseRightOfUseAssetAndLiabilities" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#LeasesDetails-LeaseTermAndDiscount" roleURI="http://focusuniversal.com/role/LeasesDetails-LeaseTermAndDiscount" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#LeasesDetails-LeaseMaturity" roleURI="http://focusuniversal.com/role/LeasesDetails-LeaseMaturity" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#LeasesDetailsNarrative" roleURI="http://focusuniversal.com/role/LeasesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#BankLoanDetails" roleURI="http://focusuniversal.com/role/BankLoanDetails" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#BankLoanDetails-MaturitiesOfLoanPayments" roleURI="http://focusuniversal.com/role/BankLoanDetails-MaturitiesOfLoanPayments" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#BankLoanDetailsNarrative" roleURI="http://focusuniversal.com/role/BankLoanDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#StockholdersEquityDetails-BlackScholesOption" roleURI="http://focusuniversal.com/role/StockholdersEquityDetails-BlackScholesOption" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#StockholdersEquityDetails-StockOptionActivity" roleURI="http://focusuniversal.com/role/StockholdersEquityDetails-StockOptionActivity" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#StockholdersEquityDetailsNarrative" roleURI="http://focusuniversal.com/role/StockholdersEquityDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#ScheduleOfSegmentReportingDetails" roleURI="http://focusuniversal.com/role/ScheduleOfSegmentReportingDetails" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#SegmentReportingDetailsNarrative" roleURI="http://focusuniversal.com/role/SegmentReportingDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="fcuv-20260630.xsd#ContingenciesDetailsNarrative" roleURI="http://focusuniversal.com/role/ContingenciesDetailsNarrative" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/Cover" xlink:title="00000001 - Document - Cover" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/CondensedConsolidatedBalanceSheets" xlink:title="00000002 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Cash" xlink:label="loc_us-gaapCash" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapCash" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaapAccountsReceivableNetCurrent" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapAccountsReceivableNetCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapInventoryNet" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherReceivablesNetCurrent" xlink:label="loc_us-gaapOtherReceivablesNetCurrent" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapOtherReceivablesNetCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="loc_us-gaapPrepaidExpenseCurrent" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapPrepaidExpenseCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketableSecurities" xlink:label="loc_us-gaapMarketableSecurities" />
      <link:calculationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapMarketableSecurities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsAssetsCurrent" xlink:label="loc_us-gaapDepositsAssetsCurrent" />
      <link:calculationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapDepositsAssetsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapAssetsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedComputerSoftwareNet" xlink:label="loc_us-gaapCapitalizedComputerSoftwareNet" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapCapitalizedComputerSoftwareNet" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositsAssetsNoncurrent" xlink:label="loc_us-gaapDepositsAssetsNoncurrent" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapDepositsAssetsNoncurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaapOtherLiabilitiesCurrent" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapOtherLiabilitiesCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayableToBankCurrent" xlink:label="loc_us-gaapLoansPayableToBankCurrent" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapLoansPayableToBankCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityCurrent" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapOperatingLeaseLiabilityCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilities" xlink:to="loc_us-gaapLiabilitiesCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermLoansFromBank" xlink:label="loc_us-gaapLongTermLoansFromBank" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilities" xlink:to="loc_us-gaapLongTermLoansFromBank" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaapOtherLiabilitiesNoncurrent" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilities" xlink:to="loc_us-gaapOtherLiabilitiesNoncurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityNoncurrent" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilities" xlink:to="loc_us-gaapOperatingLeaseLiabilityNoncurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapCommonStockValue" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonValue" xlink:label="loc_us-gaapTreasuryStockCommonValue" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapTreasuryStockCommonValue" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaapAdditionalPaidInCapital" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapAdditionalPaidInCapital" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="fcuv-20260630.xsd#FCUV_SharesToBeIssuedCommonSharesValue" xlink:label="loc_FCUVSharesToBeIssuedCommonSharesValue" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_FCUVSharesToBeIssuedCommonSharesValue" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax" />
      <link:calculationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquity" xlink:to="loc_us-gaapLiabilities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent" xlink:label="loc_us-gaapTemporaryEquityCarryingAmountAttributableToParent" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquity" xlink:to="loc_us-gaapTemporaryEquityCarryingAmountAttributableToParent" xlink:type="arc" weight="1" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquity" xlink:to="loc_us-gaapStockholdersEquity" xlink:type="arc" weight="1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:title="00000003 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss" xlink:title="00000004 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) (UNAUDITED)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaapOperatingExpenses" />
      <link:loc xlink:type="locator" xlink:href="fcuv-20260630.xsd#FCUV_PropertyOperatingExpenses" xlink:label="loc_FCUVPropertyOperatingExpenses" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_FCUVPropertyOperatingExpenses" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="loc_us-gaapOtherCostAndExpenseOperating" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapOtherCostAndExpenseOperating" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAndAmortization" xlink:label="loc_us-gaapDepreciationAndAmortization" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapDepreciationAndAmortization" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingExpense" xlink:label="loc_us-gaapSellingExpense" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapSellingExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OfficersCompensation" xlink:label="loc_us-gaapOfficersCompensation" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapOfficersCompensation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense" />
      <link:calculationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapResearchAndDevelopmentExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfessionalAndContractServicesExpense" xlink:label="loc_us-gaapProfessionalAndContractServicesExpense" />
      <link:calculationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapProfessionalAndContractServicesExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherGeneralAndAdministrativeExpense" xlink:label="loc_us-gaapOtherGeneralAndAdministrativeExpense" />
      <link:calculationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapOtherGeneralAndAdministrativeExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues" xlink:label="loc_us-gaapRevenues" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingIncomeLoss" xlink:to="loc_us-gaapRevenues" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingIncomeLoss" xlink:to="loc_us-gaapOperatingExpenses" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaapNonoperatingIncomeExpense" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="loc_us-gaapInterestIncomeExpenseNet" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNonoperatingIncomeExpense" xlink:to="loc_us-gaapInterestIncomeExpenseNet" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:label="loc_us-gaapMarketableSecuritiesUnrealizedGainLoss" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNonoperatingIncomeExpense" xlink:to="loc_us-gaapMarketableSecuritiesUnrealizedGainLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiRealizedGainLoss" xlink:label="loc_us-gaapEquitySecuritiesFvNiRealizedGainLoss" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNonoperatingIncomeExpense" xlink:to="loc_us-gaapEquitySecuritiesFvNiRealizedGainLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaapOtherNonoperatingIncomeExpense" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNonoperatingIncomeExpense" xlink:to="loc_us-gaapOtherNonoperatingIncomeExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapOperatingIncomeLoss" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapNonoperatingIncomeExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="loc_us-gaapNetIncomeLossAvailableToCommonStockholdersBasic" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="loc_us-gaapNetIncomeLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockAccretionOfRedemptionDiscount" xlink:label="loc_us-gaapPreferredStockAccretionOfRedemptionDiscount" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="loc_us-gaapPreferredStockAccretionOfRedemptionDiscount" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaapComprehensiveIncomeNetOfTax" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapComprehensiveIncomeNetOfTax" xlink:to="loc_us-gaapNetIncomeLossAvailableToCommonStockholdersBasic" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax" xlink:label="loc_us-gaapOtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapComprehensiveIncomeNetOfTax" xlink:to="loc_us-gaapOtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentBeforeTax" xlink:type="arc" weight="1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfRedeemablePreferredStockAndStockholdersEquity" xlink:title="00000005 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE PREFERRED STOCK AND STOCKHOLDERS&apos; EQUITY (UNAUDITED)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:title="00000006 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapNetIncomeLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryLIFOReservePeriodCharge" xlink:label="loc_us-gaapInventoryLIFOReservePeriodCharge" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapInventoryLIFOReservePeriodCharge" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaapDepreciation" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapDepreciation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentForAmortization" xlink:label="loc_us-gaapAdjustmentForAmortization" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapAdjustmentForAmortization" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:label="loc_us-gaapMarketableSecuritiesUnrealizedGainLoss" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapMarketableSecuritiesUnrealizedGainLoss" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiRealizedGainLoss" xlink:label="loc_us-gaapEquitySecuritiesFvNiRealizedGainLoss" />
      <link:calculationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapEquitySecuritiesFvNiRealizedGainLoss" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation" />
      <link:calculationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapShareBasedCompensation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense" />
      <link:calculationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaapIncreaseDecreaseInAccountsReceivable" />
      <link:calculationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInAccountsReceivable" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaapIncreaseDecreaseInInventories" />
      <link:calculationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInInventories" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherReceivables" xlink:label="loc_us-gaapIncreaseDecreaseInOtherReceivables" />
      <link:calculationArc order="11" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInOtherReceivables" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:label="loc_us-gaapIncreaseDecreaseInPrepaidExpense" />
      <link:calculationArc order="12" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInPrepaidExpense" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="fcuv-20260630.xsd#FCUV_IncreaseDecreaseInDeposit" xlink:label="loc_FCUVIncreaseDecreaseInDeposit" />
      <link:calculationArc order="13" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_FCUVIncreaseDecreaseInDeposit" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseImpairmentLoss" xlink:label="loc_us-gaapOperatingLeaseImpairmentLoss" />
      <link:calculationArc order="14" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapOperatingLeaseImpairmentLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaapIncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" />
      <link:calculationArc order="15" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOtherCurrentLiabilities" xlink:label="loc_us-gaapIncreaseDecreaseInOtherCurrentLiabilities" />
      <link:calculationArc order="16" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInOtherCurrentLiabilities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability" xlink:label="loc_us-gaapIncreaseDecreaseInOperatingLeaseLiability" />
      <link:calculationArc order="17" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInOperatingLeaseLiability" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInInvestingActivities" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaapPaymentsToAcquirePropertyPlantAndEquipment" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInInvestingActivities" xlink:to="loc_us-gaapPaymentsToAcquirePropertyPlantAndEquipment" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireSoftware" xlink:label="loc_us-gaapPaymentsToAcquireSoftware" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInInvestingActivities" xlink:to="loc_us-gaapPaymentsToAcquireSoftware" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities" xlink:label="loc_us-gaapProceedsFromSaleAndMaturityOfMarketableSecurities" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInInvestingActivities" xlink:to="loc_us-gaapProceedsFromSaleAndMaturityOfMarketableSecurities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock" xlink:label="loc_us-gaapPaymentsForRepurchaseOfPreferredStockAndPreferenceStock" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapPaymentsForRepurchaseOfPreferredStockAndPreferenceStock" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfBankDebt" xlink:label="loc_us-gaapRepaymentsOfBankDebt" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapRepaymentsOfBankDebt" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="fcuv-20260630.xsd#FCUV_SharesIssuedForPrefundedUnits" xlink:label="loc_FCUVSharesIssuedForPrefundedUnits" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_FCUVSharesIssuedForPrefundedUnits" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:label="loc_us-gaapProceedsFromIssuanceOfPrivatePlacement" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapProceedsFromIssuanceOfPrivatePlacement" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaapPaymentsForRepurchaseOfCommonStock" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapPaymentsForRepurchaseOfCommonStock" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="loc_us-gaapNetCashProvidedByUsedInInvestingActivities" xlink:type="arc" weight="1" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaapEffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="loc_us-gaapEffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:type="arc" weight="1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/OrganizationAndOperations" xlink:title="999012 - Disclosure - Organization and Operations" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPolicies" xlink:title="999013 - Disclosure - Summary of Significant Accounting Policies" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/RecentAccountingPronouncements" xlink:title="999014 - Disclosure - Recent Accounting Pronouncements" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/Inventory" xlink:title="999015 - Disclosure - Inventory" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/PropertyAndEquipment" xlink:title="999016 - Disclosure - Property and Equipment" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/RentalOperations" xlink:title="999017 - Disclosure - Rental Operations" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquity" xlink:title="999018 - Disclosure - Series B Redeemable Preferred Stock (Temporary Equity)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/Leases" xlink:title="999019 - Disclosure - Leases" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/BankLoan" xlink:title="999020 - Disclosure - Bank Loan" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/StockholdersEquity" xlink:title="999021 - Disclosure - Stockholders&#8217; Equity" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SegmentReporting" xlink:title="999022 - Disclosure - Segment Reporting" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/Contingencies" xlink:title="999023 - Disclosure - Contingencies" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SubsequentEvents" xlink:title="999024 - Disclosure - Subsequent Events" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:title="999025 - Disclosure - Summary of Significant Accounting Policies (Policies)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:title="999026 - Disclosure - Summary of Significant Accounting Policies (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/InventoryTables" xlink:title="999027 - Disclosure - Inventory (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/PropertyAndEquipmentTables" xlink:title="999028 - Disclosure - Property and Equipment (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/RentalOperationsTables" xlink:title="999029 - Disclosure - Rental Operations (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityTables" xlink:title="999030 - Disclosure - Series B Redeemable Preferred Stock (Temporary Equity) (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/LeasesTables" xlink:title="999031 - Disclosure - Leases (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/BankLoanTables" xlink:title="999032 - Disclosure - Bank Loan (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/StockholdersEquityTables" xlink:title="999033 - Disclosure - Stockholders&#8217; Equity (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SegmentReportingTables" xlink:title="999034 - Disclosure - Segment Reporting (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/OrganizationAndOperationsDetailsNarrative" xlink:title="999035 - Disclosure - Organization and Operations (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-fairValueRecurringBasis" xlink:title="999036 - Disclosure - Summary of Significant Accounting Policies (Details-Fair value recurring basis)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-AntidilutiveShares" xlink:title="999037 - Disclosure - Summary of Significant Accounting Policies (Details - Antidilutive shares)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetails-ForeignCurrencyTranslation" xlink:title="999038 - Disclosure - Summary of Significant Accounting Policies (Details - Foreign Currency Translation)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:title="999039 - Disclosure - Summary of Significant Accounting Policies (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/InventoryDetails-Inventory" xlink:title="999040 - Disclosure - Inventory (Details - Inventory)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryFinishedGoods" xlink:label="loc_us-gaapInventoryFinishedGoods" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapInventoryNet" xlink:to="loc_us-gaapInventoryFinishedGoods" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryValuationReserves" xlink:label="loc_us-gaapInventoryValuationReserves" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapInventoryNet" xlink:to="loc_us-gaapInventoryValuationReserves" xlink:type="arc" weight="-1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/PropertyAndEquipmentDetails-PropertyAndEquipment" xlink:title="999041 - Disclosure - Property and Equipment (Details - Property and equipment)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/PropertyAndEquipmentDetailsNarrative" xlink:title="999042 - Disclosure - Property and Equipment (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/RentalOperationsDetails-FutureRents" xlink:title="999043 - Disclosure - Rental Operations (Details - Future rents)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/RentalOperationsDetailsNarrative" xlink:title="999044 - Disclosure - Rental Operations (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityDetails-BalanceSheetReconciled" xlink:title="999045 - Disclosure - Series B Redeemable Preferred Stock (Temporary Equity) (Details - Balance sheet reconciled)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SeriesBRedeemablePreferredStockTemporaryEquityDetailsNarrative" xlink:title="999046 - Disclosure - Series B Redeemable Preferred Stock (Temporary Equity) (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/LeasesDetails-OperatingLeaseRightOfUseAssetAndLiabilities" xlink:title="999047 - Disclosure - Leases (Details - Operating lease right of use asset and liabilities)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/LeasesDetails-LeaseTermAndDiscount" xlink:title="999048 - Disclosure - Leases (Details - Lease term and discount)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/LeasesDetails-LeaseMaturity" xlink:title="999049 - Disclosure - Leases (Details - Lease maturity)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/LeasesDetailsNarrative" xlink:title="999050 - Disclosure - Leases (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/BankLoanDetails" xlink:title="999051 - Disclosure - Bank Loan (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/BankLoanDetails-MaturitiesOfLoanPayments" xlink:title="999052 - Disclosure - Bank Loan (Details - Maturities of loan payments)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/BankLoanDetailsNarrative" xlink:title="999053 - Disclosure - Bank Loan (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/StockholdersEquityDetails-BlackScholesOption" xlink:title="999054 - Disclosure - Stockholders&apos; Equity (Details - Black Scholes Option)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/StockholdersEquityDetails-StockOptionActivity" xlink:title="999055 - Disclosure - Stockholders&apos; Equity (Details - Stock option activity)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/StockholdersEquityDetailsNarrative" xlink:title="999056 - Disclosure - Stockholders&#8217; Equity (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/ScheduleOfSegmentReportingDetails" xlink:title="999057 - Disclosure - Schedule of segment reporting (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/SegmentReportingDetailsNarrative" xlink:title="999058 - Disclosure - Segment Reporting (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://focusuniversal.com/role/ContingenciesDetailsNarrative" xlink:title="999059 - Disclosure - Contingencies (Details Narrative)" />
</link:linkbase>
