GS1 Check Digit Calculator

How to use this calculator

Start with the deterministic fixture values already shown, then replace each input with measurements from your job. Use consistent units and review the highlighted assumptions before using the result in purchasing or production.

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.

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

• GS1: How to calculate a check digit manually

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