VIN Check Digit Calculator
Enter a 17-character VIN to compute its check digit (position 9) using the ISO 3779 weighted mod-11 formula, and instantly verify whether the VIN is mathematically valid.
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How the check digit is calculated
- Each of the 17 characters is converted to a number using the ISO 3779 transliteration table (letters map to 1–9; I, O, and Q are not used).
- Each value is multiplied by its position weight: 8 7 6 5 4 3 2 10 0 9 8 7 6 5 4 3 2.
- All 17 products are added together.
- The sum is divided by 11. The remainder is the check digit — and a remainder of 10 is written as
X.
Note that position 9 has a weight of 0, so the check digit never depends on itself. Want the full picture? Read what a VIN is and what each part means, or decode a VIN to see the full vehicle details.