VIN Check Digit Calculator
Calculate a VIN's check digit (position 9), or validate that an existing VIN's check digit is correct.
Overview
Every 17-character VIN's 9th character is a check digit computed from the other 16 — required on all vehicles sold in North America since 1981. Each character is transliterated to a numeric value (letters I, O, and Q are never used, to avoid confusion with 1 and 0), multiplied by a fixed per-position weight, summed, and reduced mod 11 — a remainder of 10 becomes the letter 'X'.
Examples
Calculate the check digit
1M8GDM90KP042788
Expected check digit (position 9): X
Validate an existing VIN
1M8GDM9AXKP042788
Valid — check digit X matches
How It Works
- Choose Calculate (find the expected check digit) or Validate (check an existing VIN).
- Enter a 17-character VIN — in Calculate mode, position 9 can be anything, since it's recomputed.
- The result shows the expected check digit, or whether the VIN's existing one matches.
Use Cases
Spotting a mistyped VIN
A VIN with a wrong check digit is a strong signal it was mistyped or altered — validate it before relying on it.
Cross-checking title and registration paperwork
Confirm a VIN printed on a document is internally consistent before assuming it's genuine.
Tips
- This checks the VIN's own internal consistency, not whether it belongs to a real, existing vehicle — use the VIN Decoder for that.
FAQ
No. Every calculation runs locally in your browser.
VINs are exactly 17 characters and never use the letters I, O, or Q, to avoid confusion with 1 and 0 — anything else is rejected as malformed before the checksum is even computed.