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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2021-02-09</periodOfReport>

    <dateOfOriginalSubmission>2021-02-11</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001819035</issuerCik>
        <issuerName>Metromile, Inc.</issuerName>
        <issuerTradingSymbol>MILE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001619941</rptOwnerCik>
            <rptOwnerName>Friedberg David A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O METROMILE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>425 MARKET STREET, SUITE 700</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>867438</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>867438</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1109062</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1109062</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-09</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4564478</value>
                    <footnoteId id="F6"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4564478</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F7"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Received pursuant to the Agreement and Plan of Merger and Reorganization, dated as of November 24, 2020, as amended January 12, 2021 and further amended February 8, 2021, by and among INSU Acquisition Corp. II (n/k/a Metromile, Inc.) (the &quot;Issuer&quot;), INSU II Merger Sub Corp. and MetroMile, Inc. (n/k/a Metromile Operating Company) (&quot;Legacy Metromile&quot;) (the &quot;Merger Agreement&quot;) pursuant to which, through a series of mergers Legacy Metromile became a direct, wholly-owned subsidiary of the Issuer. Pursuant to the Merger Agreement former securityholders of Legacy Metromile will receive additional shares of the Issuer's common stock (the &quot;Additional Shares&quot;) if the closing sale price of the Issuer's common stock exceeds $15.00 per share for 20 out of any 30 consecutive trading days during the first two years following the closing of the merger. The transactions contemplated by the Merger Agreement are referred to herein as the &quot;Business Combination.&quot;</footnote>
        <footnote id="F2">Includes 91,241 shares to be received as Additional Shares.</footnote>
        <footnote id="F3">The shares are held by The Friedberg Irrevocable Remainder Trust u/a/d 5/17/2017, of which Mr. Friedberg is the trustee.</footnote>
        <footnote id="F4">Includes 118,017 shares to be received as Additional Shares.</footnote>
        <footnote id="F5">The shares are held by The David Friedberg 2019 Annuity Trust u/a/d 9/26/19, of which Mr. Friedberg is the trustee.</footnote>
        <footnote id="F6">Includes 485,714 shares to be received as Additional Shares.</footnote>
        <footnote id="F7">The shares are held by The David Friedberg Revocable Trust u/a/d 9/19/13, of which Mr. Friedberg is the trustee.</footnote>
    </footnotes>

    <remarks>This amendment is being filed to correct the share amounts received in the Business Combination resulting from a post-closing correction to the final exchange ratio.</remarks>

    <ownerSignature>
        <signatureName>/s/ Winston Macaraeg, Attorney-in-Fact</signatureName>
        <signatureDate>2021-03-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
