Donaldson R F Barcode Check Digit Calculator
Work out the last digit of an EAN, UPC or GTIN barcode — or check that a full code is valid.
How the check digit is calculated
EAN-13, EAN-8, UPC-A, GTIN-14 and SSCC-18 all use the same GS1 method. Starting from the digit next to the check digit and working left, multiply the digits alternately by 3 and 1; add the results; the check digit is the number that brings the total up to the next multiple of ten (0 if it is already one). For example, 400638133393 gives 4×1 + 0×3 + 0×1 + 6×3 + 3×1 + 8×3 + 1×1 + 3×3 + 3×1 + 3×3 + 9×1 + 3×3 = 89 (working from the left with weights 1 and 3 for a 12-digit start), so the check digit is 1 and the full EAN-13 is 4006381333931.
Enter the digits without the check digit to calculate it, and use the digit count to identify the format: 7 digits → EAN-8, 11 → UPC-A, 12 → EAN-13, 13 → GTIN-14, 17 → SSCC-18. To verify a full code, switch to “Verify” and paste the whole number (8, 12, 13, 14 or 18 digits). Spaces and hyphens are ignored. An ISBN-13 book code is an EAN-13 starting 978 or 979, so it works here too. A correct check digit only proves the number was typed correctly: it does not prove the product is registered with GS1, and the first digits do not reliably tell you the country of manufacture. To draw the barcode, use our Barcode Generator.