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GS1 Check Digit Calculator

Calculate a missing GS1 check digit or check the final digit of an existing number.

Example values are filled in. Change them to match your job; results update automatically.

How to use this tool ↓

Your inputs

Replace the example values with your own.

GTIN-8, GTIN-12 / UPC-A, GTIN-13, GTIN-14 or SSCC-18
One complete identifier per line, or separate values with commas. Maximum 100.

Calculated result

Identifier typeGTIN-13
Check digit1
Complete identifier4006381333931
From rightmost body digit: 3×3 + 9×1 + 3×3 + 3×1 + 3×3 + 1×1 + 8×3 + 3×1 + 6×3 + 0×1 + 0×3 + 4×1 = 89\nCheck digit = (10 − (89 mod 10)) mod 10 = 1
This independent calculator implements the standard modulo-10 arithmetic. It does not confer GS1 ownership, allocation or certification.

How to use this calculator

  1. Choose calculation for a missing final digit, or validation for a complete identifier. The tool detects the type from its length.
  2. Enter the digits exactly as supplied, keeping any leading zeros.
  3. Read the completed number or validation result. For several numbers, use the batch input and enter one per line.

A valid check digit does not prove that an identifier is registered, assigned to you or linked to a real product.

Formula and method

Starting at the rightmost body digit, multiply alternating digits by 3 and 1, sum the products, and choose the digit that brings the sum to the next multiple of ten: (10 − (sum mod 10)) mod 10.

Read the methodology and source notes →

Read the complete how to calculate a gs1 check digit guide →

Worked example

For GTIN-13 body 400638133393, the alternating weighted sum is 89, so the check digit is 1 and the complete identifier is 4006381333931.

How to interpret the result

A valid check digit catches many transcription errors. It does not prove that an identifier was properly licensed, allocated or assigned.

Supported GS1 identifier lengths

Calculate or validate GTIN-8 (also represented by EAN-8), GTIN-12 (UPC-A), GTIN-13 (EAN-13), GTIN-14 and SSCC-18 check digits. Select the action explicitly because some complete lengths overlap with another identifier's body length.

A matching check digit confirms only the modulo-10 arithmetic. It does not confirm that a number was allocated to a company or product.

Known calculation examples

Use these complete identifiers to check an implementation or spreadsheet. Leading zeros are part of the identifier and must not be removed.

IdentifierBodyCheck digitComplete value
GTIN-89638507496385074
UPC-A / GTIN-12036000291452036000291452
GTIN-1340063813339314006381333931
GTIN-141001234500001710012345000017
SSCC-18106141411234567897106141411234567897

Validate multiple identifiers

The optional batch field validates up to 100 complete identifiers locally in the browser. It reports the expected corrected value when the final digit does not match, without checking allocation or ownership.

Limitations

Only the numeric lengths listed are accepted. Application identifiers, element strings, Digital Link syntax and company-prefix allocation are outside this calculator.

Primary references

Related tools

Related guides

Usage instructions updated October 19, 2026.
Last reviewed: