Acme United (ACU) S-8 Registration of securities for employees

Exhibit 23.1

Consent of Marcum LLP, Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement of ACME United Corporation on Form S-8 of our report dated March 15, 2018, with respect to our audits of the consolidated financial statements of ACME United Corporation as of December 31, 2017 and 2016 and for the years then ended and our report dated March 15, 2018 with respect to our audit of the effectiveness of internal control over financial reporting of ACME United Corporation as of December 31, 2017, which reports are included in the Annual Report on Form 10-K of ACME United Corporation for the year ended December 31, 2017.

/s/ Marcumllp

Marcumllp

New Haven, Connecticut

August 31, 2018