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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-02-27</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001382821</issuerCik>
        <issuerName>Redfin Corp</issuerName>
        <issuerTradingSymbol>RDFN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001413877</rptOwnerCik>
            <rptOwnerName>Greylock XII GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2550 SAND HILL ROAD, SUITE 200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Former 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001413950</rptOwnerCik>
            <rptOwnerName>Greylock XII Limited Partnership</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2550 SAND HILL ROAD, SUITE 200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Former 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001496057</rptOwnerCik>
            <rptOwnerName>Greylock XII-A Limited Partnership</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2550 SAND HILL ROAD, SUITE 200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Former 10% Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1859625</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5618937</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Greylock XII Limited Partnership</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-02-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>206625</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>624325</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Greylock XII-A Limited Partnership</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents a pro-rata, in-kind distribution by Greylock XII Limited Partnership (&quot;Greylock XII LP&quot;) and its affiliated funds and associated persons, without additional consideration, to their respective partners, members and assigns.  Such distribution  was made in accordance with the exemption afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended.</footnote>
        <footnote id="F2">The shares are held directly by Greylock XII LP. Greylock XII GP Limited Liability Company (&quot;Greylock XII GP&quot;) is the sole General Partner of Greylock XII LP and may be deemed to share voting and dispositive power with respect to the shares held by Greylock XII LP. Greylock XII GP disclaims beneficial ownership of the securities held by Greylock XII LP except to the extent of any pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission by Greylock XII GP of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F3">Represents a pro-rata, in-kind distribution by Greylock XII-A Limited Partnership (&quot;Greylock XII-A LP&quot;) and its affiliated funds and associated persons, without additional consideration, to their respective partners, members and assigns. Such distribution was made in accordance with the exemption afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended.</footnote>
        <footnote id="F4">The shares are held directly by Greylock XII-A LP. Greylock XII GP is the sole General Partner of Greylock XII-A LP and may be deemed to share voting and dispositive power with respect to the shares held by Greylock XII-A LP. Greylock XII GP disclaims beneficial ownership of the securities held by Greylock XII-A LP except to the extent of any pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission by Greylock XII GP of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Donald A. Sullivan, as Administrative Partner of Greylock XII GP LLC</signatureName>
        <signatureDate>2018-03-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Donald A. Sullivan, as Administrative Partner of Greylock XII GP LLC, the general partner of Greylock XII Limited Partnership</signatureName>
        <signatureDate>2018-03-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Donald A. Sullivan, as Administrative Partner of Greylock XII GP LLC, the general partner of Greylock XII-A Limited Partnership</signatureName>
        <signatureDate>2018-03-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
