-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 EmOx8k2RAQsZfCpRSJjWhsI9obdxu6yK+5XDTBfLIA3x+1gqVi2VJC2a6z4SxgMZ
 CWfV/awelxAXoT+XbIjcYA==

<SEC-DOCUMENT>0001026608-05-000049.txt : 20050502
<SEC-HEADER>0001026608-05-000049.hdr.sgml : 20050502
<ACCEPTANCE-DATETIME>20050502181837
ACCESSION NUMBER:		0001026608-05-000049
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050428
FILED AS OF DATE:		20050502
DATE AS OF CHANGE:		20050502

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACME UNITED CORP
		CENTRAL INDEX KEY:			0000002098
		STANDARD INDUSTRIAL CLASSIFICATION:	CUTLERY, HANDTOOLS & GENERAL HARDWARE [3420]
		IRS NUMBER:				060236700
		STATE OF INCORPORATION:			CT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1931 BLACK ROCK TURNPIKE
		CITY:			FAIRFIELD
		STATE:			CT
		ZIP:			06825
		BUSINESS PHONE:		2033327330

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ACME SHEAR CO
		DATE OF NAME CHANGE:	19710713

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			JOHNSEN WALTER C
		CENTRAL INDEX KEY:			0001014360
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-07698
		FILM NUMBER:		05792311

	BUSINESS ADDRESS:	
		STREET 1:		ACME UNITED CORP
		STREET 2:		1931 BLACK ROCK TURNPIKE
		CITY:			FAIRFIELD
		STATE:			CT
		ZIP:			06825
		BUSINESS PHONE:		2033327330

	MAIL ADDRESS:	
		STREET 1:		C/O ACME UNITED CORP
		STREET 2:		1931 BLACK ROCK TURNPIKE
		CITY:			FAIRFIELD
		STATE:			CT
		ZIP:			06825
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-04-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000002098</issuerCik>
        <issuerName>ACME UNITED CORP</issuerName>
        <issuerTradingSymbol>ACU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001014360</rptOwnerCik>
            <rptOwnerName>JOHNSEN WALTER C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACME UNITED CORP</rptOwnerStreet1>
            <rptOwnerStreet2>1931 BLACK ROCK TURNPIKE</rptOwnerStreet2>
            <rptOwnerCity>FAIRFIELD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06825</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.65</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-04-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>20000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.65</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-04-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">5,000 shares will vest on April 29, 2005, 5,000 shares will vest on April 29, 2006, 5,000 shares will vest on April 29, 2007 and 5,000 shares will vest on April 29, 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Walter C. Johnsen</signatureName>
        <signatureDate>2005-05-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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