GS1 check digit calculator
Calculate or verify the check digit of a UPC, GTIN, GLN or SSCC before it goes on a label or into an 856.
- UPC, EAN, GTIN-14
- GLN and SSCC-18
- Working shown
Enter the number without its last digit (7, 11, 12, 13, 16 or 17 digits).
Reference
GS1 numbers you meet in EDI
| Number | Digits | Identifies | Where it goes in EDI |
|---|---|---|---|
| GTIN-12 (UPC-A) | 12 | Retail item | Qualifier UP in PO1, IT1 or LIN |
| GTIN-13 (EAN) | 13 | Retail item outside North America | Qualifier EN; EDIFACT item type EN |
| GTIN-14 | 14 | Case or inner pack | Qualifier UK, often on the 856 pack level |
| GLN | 13 | Company or location | N1 qualifier UL; EDIFACT NAD, agency 9 |
| SSCC-18 | 18 | Carton or pallet | 856 MAN*GM, after application identifier 00 |
FAQ
Check digit questions
How is a GS1 check digit calculated?
Starting from the right of the number without its check digit, multiply the digits alternately by 3 and 1 and add the results. The check digit is the amount needed to reach the next multiple of 10 (0 if the sum already is one). The same method works for every GTIN, the GLN and the SSCC.
Why does a wrong check digit matter in EDI?
Retailers and distributors scan barcodes and match them against the GTINs and SSCCs in your 856 ship notice. A wrong digit means the carton or item does not match, which can lead to manual receiving, chargebacks or a rejected ASN.
Is a 13-digit number a GTIN or a GLN?
Both use 13 digits and the same check digit. A GTIN-13 identifies a product; a GLN identifies a company or a location such as a ship-to dock. The context tells them apart: product ID fields carry GTINs, party fields such as N1 carry GLNs.
Does this tool create barcodes or assign numbers?
No. It calculates and checks check digits only. Your company prefix and numbers come from GS1, and barcodes are printed by your labeling software.
Labels and ASNs that match, every time
Comparatio builds your 856 maps so the SSCCs and GTINs in the ship notice match the cartons on the truck.