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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-09-29</periodOfReport>

    <issuer>
        <issuerCik>0001652044</issuerCik>
        <issuerName>Alphabet Inc.</issuerName>
        <issuerTradingSymbol>GOOG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001295032</rptOwnerCik>
            <rptOwnerName>Brin Sergey</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ALPHABET INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1600 AMPHITHEATRE PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>MOUNTAIN VIEW</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <officerTitle>President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>Class A Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2016-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>16666</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16666</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2016-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
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            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>801.9288</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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                <transactionFormType>4</transactionFormType>
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            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                    <value>14034</value>
                </sharesOwnedFollowingTransaction>
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        <nonDerivativeTransaction>
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            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
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            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
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                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                    <footnoteId id="F6"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
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            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
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                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
                    <value>5721</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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                <value>Class A Common Stock</value>
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            <transactionCoding>
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        <nonDerivativeTransaction>
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            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19842041</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class C Capital Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>783.642</value>
                    <footnoteId id="F22"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19841041</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class C Capital Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2016-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>785.42</value>
                    <footnoteId id="F23"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19840541</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>16666</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F24"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F25"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>16666</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>19780472</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Class A Common Stock was issued upon the conversion of one share of Class B Common Stock at the election of the Reporting Person.</footnote>
        <footnote id="F2">The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $801.30 to $802.29, inclusive. The Reporting Person undertakes to provide to any security holder of Alphabet Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (2) through (23) to this Form 4.</footnote>
        <footnote id="F3">The shares were sold in multiple transactions at prices ranging from $802.32 to $803.31, inclusive.</footnote>
        <footnote id="F4">The shares were sold in multiple transactions at prices ranging from $803.34 to $804.33, inclusive.</footnote>
        <footnote id="F5">The shares were sold in multiple transactions at prices ranging from $804.50 to $805.49, inclusive.</footnote>
        <footnote id="F6">The shares were sold in multiple transactions at prices ranging from $805.51 to $806.50, inclusive.</footnote>
        <footnote id="F7">The shares were sold in multiple transactions at prices ranging from $806.61 to $807.60, inclusive.</footnote>
        <footnote id="F8">The shares were sold in multiple transactions at prices ranging from $807.64 to $808.63, inclusive.</footnote>
        <footnote id="F9">The shares were sold in multiple transactions at prices ranging from $808.67 to $809.66, inclusive.</footnote>
        <footnote id="F10">The shares were sold in multiple transactions at prices ranging from $809.74 to $810.73, inclusive.</footnote>
        <footnote id="F11">The shares were sold in multiple transactions at prices ranging from $811.03 to $812.02, inclusive.</footnote>
        <footnote id="F12">The shares were sold in multiple transactions at prices ranging from $812.34 to $813.33, inclusive.</footnote>
        <footnote id="F13">The shares were sold in multiple transactions at prices ranging from $813.71 to $814.70, inclusive.</footnote>
        <footnote id="F14">The shares were sold in multiple transactions at prices ranging from $774.49 to $775.48, inclusive.</footnote>
        <footnote id="F15">The shares were sold in multiple transactions at prices ranging from $775.57 to $776.56, inclusive.</footnote>
        <footnote id="F16">The shares were sold in multiple transactions at prices ranging from $776.61 to $777.60, inclusive.</footnote>
        <footnote id="F17">The shares were sold in multiple transactions at prices ranging from $777.80 to $778.79, inclusive.</footnote>
        <footnote id="F18">The shares were sold in multiple transactions at prices ranging from $778.82 to $779.81, inclusive.</footnote>
        <footnote id="F19">The shares were sold in multiple transactions at prices ranging from $779.94 to $780.93, inclusive.</footnote>
        <footnote id="F20">The shares were sold in multiple transactions at prices ranging from $781.00 to $781.99, inclusive.</footnote>
        <footnote id="F21">The shares were sold in multiple transactions at prices ranging from $782.03 to $783.02, inclusive.</footnote>
        <footnote id="F22">The shares were sold in multiple transactions at prices ranging from $783.34 to $784.33, inclusive.</footnote>
        <footnote id="F23">The shares were sold in multiple transactions at prices ranging from $785.24 to $786.23, inclusive.</footnote>
        <footnote id="F24">All shares are exercisable as of the transaction date.</footnote>
        <footnote id="F25">There is no expiration date for the Issuer's Class B Common Stock.</footnote>
    </footnotes>

    <remarks>All transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 Trading Plan adopted by the Reporting Person.</remarks>

    <ownerSignature>
        <signatureName>/s/ Valentina Margulis, as attorney-in-fact for Sergey Brin</signatureName>
        <signatureDate>2016-09-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
