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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-10-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001447669</issuerCik>
        <issuerName>TWILIO INC</issuerName>
        <issuerTradingSymbol>TWLO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001534338</rptOwnerCik>
            <rptOwnerName>Bessemer Venture Partners VII L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001540726</rptOwnerCik>
            <rptOwnerName>Deer VII &amp; Co. Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001540731</rptOwnerCik>
            <rptOwnerName>Deer VII &amp; Co. L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001459524</rptOwnerCik>
            <rptOwnerName>BVP VII SPECIAL OPPORTUNITY FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001407577</rptOwnerCik>
            <rptOwnerName>Bessemer Venture Partners VII Institutional L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVENUE, SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001677269</rptOwnerCik>
            <rptOwnerName>15 Angels LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BESSEMER VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>1865 PALMER AVE., SUITE 104</rptOwnerStreet2>
            <rptOwnerCity>LARCHMONT</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10538</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-10-26</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3084651</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>38.60</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to an underwriting agreement and in connection with the registered public offering of shares of the Issuer's Class A Common Stock, pursuant to a final prospectus dated October 20, 2016, which offering was consummated on October 26, 2016, the Funds (as defined below) sold an aggregate of 3,084,651 shares of Class A Common Stock. Bessemer Venture Partners VII Institutional LP (&quot;BVP VII Inst&quot;) sold 423,457 shares of Class A Common Stock, Bessemer Venture Partners VII, LP (&quot;BVP VII&quot;) sold 967,902 shares of Class A Common Stock, BVP VII Special Opportunity Fund LP (&quot;BVP VII SOF&quot;) sold 1,633,337 shares of Class A Common Stock, and 15 Angels, LLC (&quot;15 Angels&quot; and, together with BVP VII SOF, BVP VII Inst and BVP VII, the &quot;Funds&quot;) sold 59,955 shares of Class A Common Stock, each at a sale price of $38.60.</footnote>
        <footnote id="F2">Deer VII &amp; Co. Ltd. (&quot;Deer Ltd.&quot;) is the general partner of Deer VII &amp; Co. L.P. (&quot;Deer L.P.&quot;), which is the general partner of BVP VII Inst, BVP VII and BVP VII SOF. 15 Angels is a wholly owned subsidiary of BVP VII Inst. Deer Ltd. and Deer L.P. disclaim beneficial ownership of the securities held by the Funds, and this report shall not be deemed an admission that Deer Ltd. and Deer L.P. are the beneficial owners of such securities, except to the extent of their pecuniary interest therein, if any, by virtue of their direct and indirect general partner interests in the Funds.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of Bessemer Venture Partners VII L.P.</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of Bessemer Venture Partners VII Institutional L.P.</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P., the General Partner of BVP VII Special Opportunity Fund L.P.</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Scott Ring, General Counsel, Deer VII &amp; Co. Ltd., the General Partner of Deer VII &amp; Co. L.P</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Scott Ring, General Counsel, Deer VII &amp; Co. Ltd</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Scott Ring, Authorized Person of 15 Angels LLC</signatureName>
        <signatureDate>2016-10-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
