🔢 VIN Checksum Validator
Enter a 17-character Vehicle Identification Number to verify its check digit (position 9) using the official ISO 3779 / NHTSA check-digit algorithm — used by all North American VINs.
How the check digit is computed
Every character becomes a number, each position has a fixed weight, and the weighted sum is reduced modulo 11:
letters -> 1-9 (A=1..H=8, J=1..N=5, P=7, R=9, S=2..Z=9); digits are themselves
weights = 8 7 6 5 4 3 2 10 0 9 8 7 6 5 4 3 2
check = (sum of value x weight) mod 11, where 10 is written XThe default VIN, 1M8GDM9AXKP042788, sums to 351. 351 mod 11 is 10, so the expected digit is X, and position 9 does hold an X. Note the zero weight there: the check digit is excluded from the sum it verifies.
What a pass does and does not prove
This runs entirely in your browser against the arithmetic. It never contacts a registry, so it cannot tell you the make, model, year, mileage, title status or accident history behind a VIN - only whether the seventeen characters are internally consistent.
- I, O and Q are rejected. They are excluded from the VIN alphabet precisely because they look like 1 and 0, and the tool refuses them rather than guessing.
- A pass catches typos, not fakes. The rule is public, so anyone inventing a VIN can make one that validates.
- Outside North America, a fail is weak evidence. The check digit is mandatory for vehicles built for the US and Canada; many European and Asian-market VINs carry a filler character there and will not pass.
Frequently asked questions
What does the 9th digit of a VIN mean?
It is the check digit, computed from the other sixteen characters. Change any one of them and the arithmetic no longer agrees, which is how a mistyped VIN gets caught before it reaches a form.
Why does my VIN have an X in it?
At position 9 an X simply means the remainder came out as 10, which needs a single character to write. Elsewhere in the VIN, X is an ordinary letter worth 7.
Why does a real VIN from my car fail the check?
Usually a transcription slip - a 5 read as an S, or an 8 as a B. If the characters are certainly right, the vehicle was probably not built to the North American standard, where the check digit is required.