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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001649749</issuerCik>
        <issuerName>FB Financial Corp</issuerName>
        <issuerTradingSymbol>FBK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001684400</rptOwnerCik>
            <rptOwnerName>Ayers James W.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>211 COMMERCE STREET, SUITE 300</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NASHVILLE</rptOwnerCity>
            <rptOwnerState>TN</rptOwnerState>
            <rptOwnerZipCode>37201</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Chairman</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-25</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3200000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>39.8062</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13980000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6647</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by Ayers Asset Management, Inc.</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">As previously reported in Forms 4 filed with the Securities and Exchange Commission on November 30, 2017, January 4, 2018 and April 3, 2018, the reporting person, for no consideration, (i) transferred to Ayers Asset Management, Inc. (&quot;AAM&quot;) 2,784 shares of common stock, par value $1.00 per share (&quot;Common Stock&quot;), of FB Financial Corporation (the &quot;Company&quot;) that the Company had previously paid him as compensation for services rendered to the Company (the &quot;Transfer&quot;) and (ii) assigned to AAM his contractual right to receive an additional 5,385 shares of Common Stock that he would receive from the Company as compensation in lieu of his salary (the &quot;Assignment&quot;).</footnote>
        <footnote id="F2">(continued from footnote 1) As of May 30, 2018, (i) in separate vestings, 469 and 1,053 RSUs, vested with the underlying shares of Common Stock being issued to the respective AAM employees and being subtracted from the reporting person's indirect beneficial ownership (ii) of the 8,169 shares of Common Stock that the reporting person initially committed to transfer to AAM  pursuant to the Transfer and Assignment, AAM has received 6,500 shares of Common Stock and will continue to have a contractual right to receive from the reporting person the remaining 1,669 shares of Common Stock owed pursuant to the Assignment.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Will Martin, as Attorney-in-Fact</signatureName>
        <signatureDate>2018-05-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
