Check digit calculator
Type a number without its last digit to get the check digit, or the whole number to verify it. Every step of the GS1 calculation is shown.
GTIN-8, GTIN-12 (UPC-A), GTIN-13 (EAN-13), GTIN-14, GLN or SSCC. Spaces and dashes are ignored.
Automatic verifies 8, 12, 13, 14 and 18 digits and calculates for 7, 11, 16 and 17.
| Digit | 5 | 9 | 0 | 1 | 2 | 3 | 4 | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| × weight | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 |
| = product | 5 | 27 | 0 | 3 | 2 | 9 | 4 | 3 | 2 | 9 | 4 | 15 |
Sum 83. The next multiple of 10 is 90, so the check digit is 7.
How the GS1 check digit works
GTINs, GLNs and SSCCs all end in a check digit worked out with the same method, which GS1 publishes. Take the digits before the check digit. Starting with the one next to it and moving left, multiply them by 3, then 1, then 3, and so on, and add the results. The check digit is what you add to that sum to reach the next multiple of ten.
GS1’s own example is the number 629104150021: the weighted sum is 57, the next multiple of ten is 60, and the check digit is 3, giving 6291041500213. Type it above to see the same steps.
| Key | Digits with check digit | Barcode |
|---|---|---|
| GTIN-8 | 8 | EAN-8 |
| GTIN-12 | 12 | UPC-A |
| GTIN-13 or GLN | 13 | EAN-13 |
| GTIN-14 | 14 | ITF-14, GS1-128 |
| SSCC | 18 | GS1-128 (00) |
A correct check digit only means the number is consistent. It does not show that the number is registered to a product or company.
Questions about check digits
How is a GS1 check digit calculated?
Starting from the digit next to the check digit and moving left, multiply the digits by 3, 1, 3, 1 and so on, and add the results. The check digit is the number you add to reach the next multiple of 10 (0 if the sum already is one).
Does a correct check digit mean the number is registered?
No. It only shows the number is internally consistent, which catches most typing errors. Whether a GTIN is assigned to a product is recorded by GS1 and the brand that owns it.
My number has 12 digits. Is it a UPC or an EAN without its check digit?
Both are possible. By default 12 digits are read as a full UPC-A and checked; choose “Calculate” to treat them as the first 12 digits of an EAN-13.
Sources
- GS1: How to calculate a check digit manually
The mod 10 method (weights 3 and 1) for GTIN, GLN and SSCC check digits, with a worked example.
- GS1: Check digit calculator
GS1’s own calculator, to compare a result.