Check Digit Calculator

Your details

Each format uses its own weighting scheme. EAN/UPC/GTIN use GS1 Mod-10; credit cards, IMEI, and NPI use the Luhn algorithm; ISBN-10 uses Mod-11.
In calculate mode enter the number without its check digit. In verify mode enter the complete number and the tool tells you whether the check digit is correct.
Enter digits only. For EAN-13 calculate mode enter 12 digits. For verify mode enter all 13. ISBN-10 check digit may be X.
Check Digit
1

The computed or verified check digit

Full Number4006381333931
Algorithm UsedGS1 Mod-10 (EAN-13)
Digit Count12 (got 12)

Check digit is 1.

  • This algorithm is used for retail barcodes and ISBN-13 book numbers.
  • Append "1" to your number to form the complete, scannable code: 4006381333931.
  • Check digits catch single-digit transcription errors and most adjacent-digit transpositions (like swapping 2 and 3), but cannot detect all two-digit errors.

Next stepKeep a record of the full number including the check digit, as scanners will reject codes with a missing or incorrect check digit.

 = Powered by OnlyCalculators