EAN-13 check digit calculator

The last digit of a barcode

EAN-13 is the barcode on almost every retail product outside North America (and inside it, as GTIN-13). Its 13 digits are a GS1 company prefix, a product reference and a final check digit that scanners use to catch misreads. When you design packaging, list products on marketplaces or import a catalogue, a wrong check digit means the barcode will be rejected.

How it is calculated

Take the first 12 digits. Starting from the right, multiply them alternately by 3 and 1, and add the results. The check digit is the number you must add to reach the next multiple of 10.

Worked example

GS1's own example, 400638133393: from the right, 3×3 + 9×1 + 3×3 + 3×1 + 3×3 + 1×1 + 8×3 + 3×1 + 6×3 + 0×1 + 0×3 + 4×1 = 89. The next multiple of 10 is 90, so the check digit is 1 and the full code is 4006381333931.

Codes starting with 789 or 790 were issued in Brazil, 400–440 in Germany, 978–979 are books.

The page removes spaces and hyphens. With 12 digits it computes the check digit with the GS1 mod-10 algorithm: from the right, digits are weighted 3, 1, 3, 1…, summed, and the check digit is (10 − sum mod 10) mod 10. With 13 digits it recomputes the check digit from the first 12 and compares it with the last. The same algorithm is used for UPC, GTIN-14 and ISBN-13. Everything runs in your browser.