CheckDigit
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GS1 Mod-10 utility

GTIN-14 check digit calculator

Enter 13 body digits to generate a 14-digit GTIN-14, or switch to Validate and enter all 14 digits. Leading zeros are preserved.

GTIN-14 worked example

How to calculate a GTIN-14 check digit

  1. Enter the 13 body digits. Starting at the rightmost body digit, apply alternating weights of 3 and 1.
  2. For body 1001234500001, the weighted products add to 33. The next multiple of 10 is 40.
  3. 40 − 33 = 7, so append check digit 7 to make the complete GTIN-14 value 10012345000017.

Generate accepts 13 body digits; Validate accepts all 14 digits. This arithmetic does not issue or look up a GTIN, convert an ASIN or UPC, prove authenticity, or confirm a product assignment.

Exact GTIN-14 calculationBody: 1001234500001

Weighted sum = 33; (10 − 33 mod 10) mod 10 = 7.

Check digit: 7 · Complete value: 10012345000017

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GS1 Mod-10 check digit

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Enter exactly 13 ASCII digits.

A matching check digit detects some entry errors. It does not prove that an identifier was issued, assigned correctly, authentic, or linked to a particular product or location.

Supported formats

Exact lengths, one shared rule

GTIN, GLN and SSCC use the same GS1 Mod-10 arithmetic but have different required lengths. CheckDigit validates the length before calculating.