UPC-A / EAN-13 Check Digit Calculator & Validator
Enter 11 digits to get the UPC-A check digit, or 12 digits to get the EAN-13 check digit. Already have a full code? Paste all 12 or 13 digits to validate it instantly. Everything runs in your browser — nothing is sent to a server.
Only digits are accepted. Letters and symbols are filtered automatically.
How it works
Both UPC-A and EAN-13 barcodes include a check digit as their final number. Scanners use this digit to confirm the rest of the code was read correctly — if the check digit does not match, the scan is rejected.
The check digit is calculated using a weighted modulo-10 formula. For UPC-A, odd-position digits are multiplied by 3 and even-position digits by 1. For EAN-13 the weights are reversed. The results are summed and the check digit is(10 − (sum mod 10)) mod 10.
This tool only checks whether a number is mathematically valid. It does not assign, license, or register official product numbers. To obtain a legitimate GS1 barcode, contact GS1.
Frequently Asked Questions
Related Tools
A 13-digit barcode is an EAN-13
There is no separate '13-digit barcode' format to learn. A 13-digit product number is an EAN-13 (also called GTIN-13): a GS1 prefix, a product reference, and a final check digit that this calculator verifies. Worked example: for 400638133393, the weighted sum of the first 12 digits gives a check digit of 1 — so the complete, valid number is 4006381333931. If your calculated digit disagrees with the one printed on a product, the number was mistyped, not 'a different kind of barcode'.
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