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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2015-08-06</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001637207</issuerCik>
        <issuerName>Planet Fitness, Inc.</issuerName>
        <issuerTradingSymbol>PLNT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001649552</rptOwnerCik>
            <rptOwnerName>Rondeau Christopher</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PLANET FITNESS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>26 FOX RUN ROAD</rptOwnerStreet2>
            <rptOwnerCity>NEWINGTON</rptOwnerCity>
            <rptOwnerState>NH</rptOwnerState>
            <rptOwnerZipCode>03801</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Holding Units and Class B common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6652142</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Holding Units and Class B common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1936147</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Common Units of Pla-Fit Holdings, LLC  (&quot;Holding Units&quot;) and shares of Class B common stock of Planet Fitness, Inc. (the &quot;Company&quot;) reported herein were issued pursuant to a reclassification of Pla-Fit Holdings, LLC on August 5, 2015.</footnote>
        <footnote id="F2">Pursuant to the terms of the Exchange Agreement dated as of August 5, 2015 by and among the Company, Pla-Fit Holdings, LLC and the holders from time to time of Holding Units and shares of Class B common stock, the holders thereof may exchange all or a portion of their Holding Units (along with an equal number of shares of Class B common stock) for shares of Class A common stock of the Company on a one-to-one basis.The Holding Units do not expire and the holders thereof are not required to pay an exercise price in connection with exchanges. The Class B common stock provides the holder with one vote on all matters submitted to a vote of the Company's stockholders but does not entitle the holder to any of the economic rights associated with shares of the Company's Class A common stock.</footnote>
        <footnote id="F3">Represents 6,652,147 Holding Units and 6,652,147 shares of Class B common stock held by The Christopher J. Rondeau Revocable Trust of 2006, u/d/t 05/15/06. Mr. Rondeau disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F4">Represents 1,936,163 Holding Units and 1,936,163 shares of Class B common stock held by The Christopher J. Rondeau Irrevocable GST Trust of 2012, u/d/t 11/08/12. Mr. Rondeau disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>Justin Vartanian is signing on behalf of Chris Rondeau pursuant to a Power of Attorney dated July 29, 2015, which is attached hereto as an exhibit.</remarks>

    <ownerSignature>
        <signatureName>/s/ Justin Vartanian, attorney-in-fact</signatureName>
        <signatureDate>2015-08-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
