How is the EAN-13 check digit calculated
The last digit of EAN-13 is not a number filled in arbitrarily when assigning the code, but one calculated according to a fixed algorithmCheck digit. Its purpose is to let scanning devices immediately detect errors when reading.
Key points at a glance
- The check digit iscalculated, not assigned, and cannot be filled in arbitrarily
- Core of the algorithm: the first 12 digits are alternately weighted by "1, 3, 1, 3..." and summed, then take the complement of the result to 10
- Passing the check only meansthe number composition is valid, and does not mean the product is genuine
Taking 690123456789_ as an example
| Position | Digit | Weight | Product |
|---|---|---|---|
| 1 | 6 | 1 | 6 |
| 2 | 9 | 3 | 27 |
| 3 | 0 | 1 | 0 |
| … | … | … | … |
| Sum of products | 88 | ||
| Check digit: (10 − 88 mod 10) mod 10 | 2 | ||
So the complete number is 6901234567892. You can usebarcode verification toolto verify any number.
Sources and notes:The check digit algorithm is based on the GS1 General Specifications (GTIN check digit calculation rules). The sample numbers in this article are demonstration numbers generated according to the rules, not the actual codes of any company.