<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-06-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001512673</issuerCik>
        <issuerName>Square, Inc.</issuerName>
        <issuerTradingSymbol>SQ</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001544567</rptOwnerCik>
            <rptOwnerName>Meeker Mary G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1455 MARKET STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 600</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-06-23</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>27382</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28281</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8623410</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents an automatic annual restricted stock unit (RSU) award issued pursuant to the Issuer's Outside Director Compensation Policy. Each RSU represents a contingent right to receive one share of the Issuer's Class A Common Stock upon settlement. 100% of the RSUs vest on the earlier of June 23, 2017 or the Issuer's next annual meeting of stockholders.</footnote>
        <footnote id="F2">The reporting person is a managing member of KPCB DGF Associates, LLC, which is the managing member of KPCB Digital Growth Fund, LLC (&quot;KPCB Growth&quot;) and KPCB DGF Founders Fund, LLC (&quot;KPCB FF&quot;). The reporting person is deemed to hold the reported securities for the benefit of KPCB Holdings, Inc., as nominee. KPCB Holdings, Inc., as nominee, may be deemed to be the indirect beneficial owner of the securities. KPCB Holdings, Inc., as nominee, holds securities for the account of KPCB Growth and KPCB FF. The reporting person may be deemed to share voting and investment power over the securities held by KPCB Growth and KPCB FF. The reporting person disclaims beneficial ownership over such securities except to the extent of her pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F3">The reporting person is a managing member of KPCB DGF Associates, LLC, which is the managing member of KPCB Growth and KPCB FF. KPCB Holdings, Inc., as nominee, holds the stock for the account of KPCB Growth and KPCB FF. The reporting person may be deemed to share voting and investment power over the securities held by KPCB Growth and KPCB FF. The reporting person disclaims beneficial ownership over such securities except to the extent of her pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jason Gao, Attorney-in-Fact</signatureName>
        <signatureDate>2016-06-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
