    <SEC-DOCUMENT>0001564590-21-010481-index.html : 20210303
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    <ACCEPTANCE-DATETIME>20210303120146
    ACCESSION NUMBER:		0001564590-21-010481
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		16
    CONFORMED PERIOD OF REPORT:	20210303
    ITEM INFORMATION:		Results of Operations and Financial Condition
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20210303
    DATE AS OF CHANGE:		20210303

    FILER:

    	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

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-07698
    		FILM NUMBER:		21707811

    	BUSINESS ADDRESS:
    		STREET 1:		55 WALLS DRIVE
    		CITY:			FAIRFIELD
    		STATE:			CT
    		ZIP:			06824
    		BUSINESS PHONE:		203-254-6060

    	MAIL ADDRESS:
    		STREET 1:		55 WALLS DRIVE
    		CITY:			FAIRFIELD
    		STATE:			CT
    		ZIP:			06824

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	ACME SHEAR CO
    		DATE OF NAME CHANGE:	19710713
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>acu-8k_20210303.htm
    <DESCRIPTION>8-K - Q4 EARNINGS RELEASE
    <TEXT>
    Document 1 - file: acu-8k_20210303.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>2
    <FILENAME>acu-ex991_6.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 2 - file: acu-ex991_6.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>gkcajgxk4c4k000002.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
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    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>gkcajgxk4c4k000003.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
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    <SEQUENCE>5
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    <DESCRIPTION>GRAPHIC
    <TEXT>
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    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>6
    <FILENAME>acu-20210303.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA
    <TEXT>
    Document 6 - file: acu-20210303.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>7
    <FILENAME>acu-20210303_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE
    <TEXT>
    Document 7 - file: acu-20210303_lab.xml

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    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>8
    <FILENAME>acu-20210303_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE
    <TEXT>
    Document 8 - file: acu-20210303_pre.xml

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>9
    <FILENAME>acu-8k_20210303_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>11
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 11 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>12
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 12 - file: Show.js

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>13
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>14
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
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    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>16
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: MetaLinks.json

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    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>17
    <FILENAME>0001564590-21-010481-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 17 - file: 0001564590-21-010481-xbrl.zip

    </DOCUMENT>
    </SEC-DOCUMENT>