One idea, four lengths
| GTIN | Digits | Barcode | Typical use |
|---|---|---|---|
| GTIN-12 | 12 | UPC-A | Retail, US & Canada |
| GTIN-13 | 13 | EAN-13 | Retail, worldwide; books (ISBN) |
| GTIN-8 | 8 | EAN-8 | Very small packs |
| GTIN-14 | 14 | ITF-14, GS1-128 | Cases and cartons |
All GTINs can be written as 14 digits by adding leading zeros. That's how databases store them: the UPC 036000291452 is the GTIN-14 00036000291452. Adding zeros on the left doesn't change the product or the check digit.
How the check digit works
The last digit is calculated from the others with the GS1 mod-10 rule:
- Starting from the right (excluding the check digit), multiply digits alternately by 3 and 1.
- Add up the results.
- The check digit is whatever brings the total up to the next multiple of 10.
Example for UPC 03600029145_: from the right, 5×3 + 4×1 + 1×3 + 9×1 + 2×3 + 0×1 + 0×3 + 0×1 + 6×3 + 3×1 + 0×3 = 58. The next multiple of 10 is 60, so the check digit is 2 → 036000291452. Our generators do this automatically and warn you if a full number's check digit is wrong.
GTIN vs UPC vs EAN vs SKU
- GTIN is the number; UPC and EAN are barcode formats that carry it.
- A SKU is your own internal stock code. It can be anything and only means something inside your business.
- An ASIN is Amazon's catalogue ID; an FNSKU is Amazon's warehouse label code.
Where GTINs come from
GTINs are issued through GS1 member organisations. Marketplaces like Amazon and Google check them against GS1's registry. Read how to get a barcode for your product before buying.