<SEC-DOCUMENT>0001562180-21-001910.txt : 20210303
<SEC-HEADER>0001562180-21-001910.hdr.sgml : 20210303
<ACCEPTANCE-DATETIME>20210303163748
ACCESSION NUMBER:		0001562180-21-001910
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210301
FILED AS OF DATE:		20210303
DATE AS OF CHANGE:		20210303

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Geist John C
		CENTRAL INDEX KEY:			0001393650

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14092
		FILM NUMBER:		21709613

	MAIL ADDRESS:	
		STREET 1:		ONE DESIGN CENTER PLACE
		STREET 2:		SUITE 850
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BOSTON BEER CO INC
		CENTRAL INDEX KEY:			0000949870
		STANDARD INDUSTRIAL CLASSIFICATION:	MALT BEVERAGES [2082]
		IRS NUMBER:				043284048
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1226

	BUSINESS ADDRESS:	
		STREET 1:		ONE DESIGN CENTER PLACE
		STREET 2:		SUITE 850
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210
		BUSINESS PHONE:		617-368-5056

	MAIL ADDRESS:	
		STREET 1:		ONE DESIGN CENTER PLACE
		STREET 2:		SUITE 850
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primarydocument.xml
<DESCRIPTION>PRIMARY DOCUMENT
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    <schemaVersion>X0306</schemaVersion>

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    <periodOfReport>2021-03-01</periodOfReport>

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        <issuerCik>0000949870</issuerCik>
        <issuerName>BOSTON BEER CO INC</issuerName>
        <issuerTradingSymbol>SAM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001393650</rptOwnerCik>
            <rptOwnerName>Geist John C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE BOSTON BEER COMPANY, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE DESIGN CENTER PLACE</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02210</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Chief Sales Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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        <nonDerivativeTransaction>
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            <transactionDate>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>9.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1060.54</value>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
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            <transactionDate>
                <value>2021-03-01</value>
            </transactionDate>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1061.66</value>
                    <footnoteId id="F6"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4704.00</value>
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                <directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
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            <transactionDate>
                <value>2021-03-01</value>
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            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
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                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>45.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1063.93</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4659.00</value>
                    <footnoteId id="F2"/>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
            </securityTitle>
            <transactionDate>
                <value>2021-03-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>113.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1068.72</value>
                    <footnoteId id="F7"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4546.00</value>
                    <footnoteId id="F2"/>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
            </securityTitle>
            <transactionDate>
                <value>2021-03-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>48.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1071.50</value>
                    <footnoteId id="F8"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4498.00</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
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            <transactionDate>
                <value>2021-03-01</value>
            </transactionDate>
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                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>23.00</value>
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                <transactionPricePerShare>
                    <value>1072.51</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common</value>
            </securityTitle>
            <transactionDate>
                <value>2021-03-01</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
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                    <value>23.00</value>
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                <transactionPricePerShare>
                    <value>1075.92</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 45 shares is from $1063.59 to $1064.26. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F2">The shares reported include 4,452 shares of restricted stock subject to vesting conditions.</footnote>
        <footnote id="F3">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 68 shares is from $1053.36 to $1053.41. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F4">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 11 shares is from $1059.00 to $1059.23. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F5">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 9 shares is from $1060.40 to $1061.10. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F6">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 3 shares is from $1061.42 to $1062.02. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F7">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 113 shares is from $1068.38 to $1069.13. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
        <footnote id="F8">The price shown is the weighted average sale price for the transactions reported on this line. The range of sale prices for the 48 shares is from $1071.01 to $1071.95. The Filing Person will provide full information regarding the number of shares sold at each separate price upon request of the SEC, the Registrant, or a shareholder of the Registrant.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Michael G. Andrews under POA for the benefit of John C. Geist</signatureName>
        <signatureDate>2021-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
