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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-01-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001484565</issuerCik>
        <issuerName>Capnia, Inc.</issuerName>
        <issuerTradingSymbol>CAPN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001614821</rptOwnerCik>
            <rptOwnerName>Anish Bhatnagar</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3 TWIN DOLPHIN DRIVE, SUITE 160</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>REDWOOD CITY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94065</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>No securities beneficially owned</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.80</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-01-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>215125</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2016-01-11</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-01-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>215125</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>215125</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">(1)	Beginning on January 11, 2016, fifty percent (50%) of the shares subject to the Option shall vest immediately and one forty-eighth (1/48th) of the remaining shares subject to the Option shall vest monthly thereafter on the same day of the month as the date of grant, subject to Optionee's continuing to be a Service Provider on such dates; provided, however, that in the event that the Optionee's continuous status as a Service Provider is terminated by the Company without Cause (as defined below) within twelve months after a Change of Control (as defined below), 100% of the total number of shares that have not yet vested shall be immediately accelerate and vest immediately prior to such time. (Continued in Footnote 2)</footnote>
        <footnote id="F2">&quot;Cause&quot; shall mean the Optionee's repeated failure to perform his or her assigned duties or responsibilities as a Service Provider (other than a failure resulting from the Optionee's disability) after notice thereof from the Company describing the Optionee's failure to perform such duties or responsibilities; (ii) the Optionee engaging in any act of dishonesty, fraud or misrepresentation; (iii) the Optionee's violation of any federal or state law or regulation applicable to the business of the Company or its affiliates; (iv) the Optionee's breach of any confidentiality agreement or invention assignment agreement between the Optionee and the Company (or any affiliate of the Company); or (v) the Optionee being convicted of, or entering a plea of nolo contendere to, any crime or committing any act of moral turpitude. &quot;Change of Control&quot; shall have the meaning set forth in the Post-IPO Plan.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ David D. O'Toole, As Attorney-in-Fact</signatureName>
        <signatureDate>2015-01-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
