Free tool
Calculate the check digit of an EAN code
Enter a barcode without its last digit: we compute the GS1 check digit and rebuild the full code, ready to print.
Paste your digits
7, 11, 12 or 13 digits, depending on whether you are building an EAN-8, UPC-A, EAN-13 or GTIN-14.
We apply the GS1 rule
Each digit is weighted by 3 or 1 from the right, then rounded up to the next multiple of 10.
You get the full code
Copy it into your POS software, your import file or your label printer.
Save time
Your barcodes are right. Your product listings still need writing
Refect reads your supplier invoices, picks up barcodes, prices and references, and builds complete listings on Shopify or Square.
Frequently asked questions
What is a check digit for?
It is the last digit of a barcode. It is derived from the previous ones, so a scanner can instantly detect a misread or a typing mistake.
Is the calculation the same for EAN-13 and UPC?
Yes. EAN-8, UPC-A, EAN-13 and GTIN-14 all use the same 3/1 weighting from the right. Only the length changes.
Can I make up my own barcodes?
For internal use, yes. To sell in retail chains or on Amazon you need a prefix bought from GS1: a code computed here would be mathematically valid but would not belong to you.
Are my codes sent anywhere?
No. Everything is computed inside your browser, nothing reaches our servers.