EAN / GTIN barcode checker
The last digit of a barcode is computed from the others, with 3-1 weighting from the right. That is what lets a till reject a doubtful scan instead of ringing up the wrong product.
EAN-13, EAN-8, UPC-A (12 digits) and GTIN-14 are all accepted.
How the check works
- 1
Length decides the standard
8 digits for EAN-8, 12 for a North American UPC-A, 13 for EAN-13, 14 for a GTIN-14 logistics unit. The check-digit maths is identical in all four cases.
- 2
The check digit is recomputed
From the right, excluding the check digit, each digit is multiplied alternately by 3 and by 1. The check digit is whatever the total needs to reach the next multiple of ten.
- 3
The prefix is identified
The first three digits name the GS1 member organisation that issued the code to the company.
The prefix is not the country of manufacture
This is the most widespread misreading of barcodes. A 30-37 prefix means the company joined GS1 France, not that the product was made there. A French company manufacturing in Asia keeps its 3xx code.
Some prefixes name no country at all: 20-29 are reserved for in-store internal use (the codes a deli scale prints on a tray), 977 for serial publications, 978 and 979 for books, 98x and 99x for coupons.
A valid code is not a listed product
The check digit proves the digit string is internally consistent. It does not say which product sits behind it, nor whether the code is assigned at all. That requires a product database — Verified by GS1, or a commercial catalogue — and many codes in circulation are absent from them.
Frequently asked questions
What is the difference between EAN-13 and UPC?
UPC-A is the 12-digit North American format; EAN-13 is its 13-digit international extension. A UPC-A with a leading zero becomes a valid EAN-13, and the check digit is unchanged — which is why both coexist in catalogues without conflict.
Does a barcode starting with 30 come from France?
It was issued by GS1 France to a member company in France, which implies nothing about where the goods were made. The prefix identifies the issuing organisation, not the product's origin.
Can I make up a barcode for my products?
The check-digit maths is free to anyone, but an unassigned code collides with someone else's product the moment it leaves your shop. To sell through retail chains or marketplaces you need a company prefix bought from GS1. Codes 20-29 exist precisely for internal use and never leave the store.
What about GTIN-14?
It identifies a logistics unit — a case of 12 boxes, a pallet — rather than a consumer unit. It takes the product's GTIN preceded by a packaging-level indicator digit, and its check digit is computed exactly like an EAN-13's.
The same check over API
This tool runs in your browser. To run the same check from your code, in bulk or server-side, the API answers in JSON.
Read the documentation