Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 07, 2018
Document And Entity Information
Entity Registrant Name	ACME UNITED CORP
Entity Central Index Key	0000002098
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Is Entity's Reporting Status Current?	Yes
Is Entity an Emerging Growth Company?	false
Is Entity a Small Business?	true
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		3,369,061
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2018