GTIN check digit

Client

The GTIN check digit is the rightmost digit on GTIN-8, GTIN-12 (UPC-A), GTIN-13 (EAN-13), and GTIN-14 strings. When OCR misreads one symbol, the body may still be correct. This page shows pass/fail and the digit that would make the string valid.

GS1 mod-10 positions

From the check digit leftward, weights alternate 3, 1, 3, 1… The sum mod 10 must equal zero when the check digit is included. Toolcore shows expected vs actual on paste.

Privacy: every comparison runs locally in your tab. Toolcore performs no GS1 registry lookup, product database match, or price scan—checksum math only.
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GTIN‑8, UPC‑A (GTIN‑12), EAN‑13, and logistic GTIN‑14 all end with the same ISO/IEC GS1 modulus‑10 weight‑3 algorithm used by the barcode generator when it pads shortened bodies with a check digit. Alternate lengths map to retailer packaging standards (coupon GTIN‑12, carton GTIN‑14, compact GTIN‑8).

Result

Passes modulus‑10 GS1 rule for GTIN-13 (13 digits).

Common use cases

  • Fix one wrong check character without re-scanning the packaging barcode.
  • Document expected check digit in QA specs for label vendors.

Common mistakes to avoid

  • Changing the check digit without verifying company prefix assignment

    Mod-10 fix does not prove the prefix belongs to your brand in GS1.

FAQ

How is the GTIN check digit calculated?

GS1 mod-10: multiply digits by alternating 3 and 1 from the right, sum, complement mod 10—the rightmost digit must match.

Which digit is the check digit?

The rightmost digit on the full GTIN-length string (8, 12, 13, or 14).

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • gtin checksum verifier online
  • ean 13 check digit validate browser
  • upc-a modulus 10 checker locally
  • gtin 14 logistic barcode checksum
  • gs1 digit string validator no lookup

More tools

Related utilities you can open in another tab—mostly client-side.