<?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>0001775287</rptOwnerCik>
            <rptOwnerName>Graves Ryan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1127 HIGH RIDGE ROAD #132</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>STAMFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06905</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>3133471</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3133471</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>417796</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>417796</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>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1500000</value>
                    <footnoteId id="F6"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1917796</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F5"/>
                </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 333,438 shares to be received as Additional Shares.</footnote>
        <footnote id="F3">The shares are held by Saltwater Capital (&quot;Saltwater&quot;). Mr. Graves may be deemed to have voting and dispositive power over the securities held by Saltwater.</footnote>
        <footnote id="F4">Includes 44,458 shares to be received as Additional Shares.</footnote>
        <footnote id="F5">The shares are held by The Graves Irrevocable Remainder Trust (&quot;Graves Irrevocable Trust&quot;). Mr. Graves may be deemed to have voting and dispositive power over the securities held by Graves Irrevocable Trust.</footnote>
        <footnote id="F6">As previously disclosed, on November 24, 2020, the Issuer entered into subscription agreements (the &quot;Subscription Agreements&quot;) with certain investors (the &quot;PIPE investors&quot;) pursuant to which such investors agreed to purchase, immediately prior to the closing of the Business Combination, an aggregate of $170,000,000 of the Issuer's shares of common stock at a price of $10.00 per share, or an aggregate of 17,00,000 shares of common stock. Cohen &amp; Company, LLC, and its affiliates are among the PIPE Investors through a special purpose vehicle (the &quot;Cohen SPV&quot;). Graves Irrevocable Trust is a member of the Cohen SPV and has a pecuniary interest therein.</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. Mr. Graves disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein.</remarks>

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