Check digit calculator (GS1)
- Free for commercial use
- No sign-up
- Nothing uploaded
Result
Type a number to see its check digit and how it was worked out.
How the GS1 check digit works
Every GTIN and SSCC ends in a check digit worked out from the other digits. The method is the same for every length:
- Starting from the right, multiply the digits by 3, 1, 3, 1 and so on. The digit next to the check digit is multiplied by 3.
- Add up the results.
- Subtract the sum from the next multiple of 10 (or from the sum itself, if it is already a multiple of 10). The result is the check digit.
The calculator shows these steps for your number. More about what the numbers mean is in UPC, EAN and GTIN explained.
Worked example
GS1's own example takes the 12 digits 629104150021 and works out the check digit for a GTIN-13:
| Digit | 6 | 2 | 9 | 1 | 0 | 4 | 1 | 5 | 0 | 0 | 2 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| × weight | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 |
| = | 6 | 6 | 9 | 3 | 0 | 12 | 1 | 15 | 0 | 0 | 2 | 3 |
The sum is 57. The next multiple of 10 is 60, and 60 − 57 = 3, so the check digit is 3 and the full GTIN-13 is 6291041500213.
A second GS1 example, for an 18-digit SSCC: the 17 digits 37610425002123456 add up to 101, so the check digit is 110 − 101 = 9.
Which length is my number?
| Name | Digits in full | Without the check digit | Usually printed as |
|---|---|---|---|
| GTIN-8 | 8 | 7 | EAN-8, on small packs |
| GTIN-12 | 12 | 11 | UPC-A (or UPC-E, its short form) |
| GTIN-13 | 13 | 12 | EAN-13 |
| GTIN-14 | 14 | 13 | ITF-14 or GS1-128, on cases and cartons |
| SSCC-18 | 18 | 17 | GS1-128, on pallet labels |
Some counts can be read two ways, so the calculator asks which you mean:
- 12 digits can be a full GTIN-12 (a UPC-A number) or a GTIN-13 without its check digit.
- 13 digits can be a full GTIN-13 or a GTIN-14 without its check digit.
- 11 digits are worked out as a GTIN-12. If a spreadsheet dropped a leading 0 from a UPC-A, the calculator says so.
A valid check digit is not a registered number
A check digit only catches typing and scanning mistakes. Any string of digits can be given a correct check digit, so a valid result doesn't mean the number belongs to your company, or to anyone. To sell in most stores, or on Amazon as the brand, you need a number from GS1. Read Do I need a GS1 barcode?
Once you have the number, "Make a barcode with this number" opens the UPC generator for a UPC-A, EAN-13 or EAN-8 barcode, or the barcode generator for ITF-14 or GS1-128.
Questions
Is a UPC check digit the same as an EAN one?
Yes. Both use the same GS1 method. A UPC-A number with a 0 added at the front is the same number as an EAN-13, and its check digit stays the same, because the weights start from the right.
Does a valid check digit mean the number is registered?
No. It only means the digits are consistent. Whether a number was issued to a company is a question for GS1, not for the check digit.
Can I check a whole list?
Yes. Choose "Verify a list" and paste one code per line. Each line gets a verdict and, where it is wrong, the check digit it should have. You can copy the results or download them as a CSV file. The list is checked in your browser and is not uploaded.
Is this the Luhn or the container check digit?
No. This calculator uses the GS1 method only. Luhn check digits, used on payment card numbers, and the check digits on shipping containers (ISO 6346) are worked out differently, so this page gives the wrong answer for them.
Sources
- GS1 General Specifications Standard, Release 26.0, January 2026: section 7.9.1; Tables 5-43, 7-8 and 7-9.
- GS1: How to calculate a check digit manually (the worked example).