VIN Check Digit Validator and Year Decoder

Every 17-character VIN has a built-in “check digit” in position 9 that proves the other 16 characters are correct. This free tool recalculates that check digit with the official ISO 3779 formula and tells you instantly whether a VIN is valid or was mistyped. It also reads the model year from the VIN. Everything runs in your browser, so the VIN you type never leaves the page.

What the check digit is

Positions 1 to 8 and 10 to 17 of a VIN each get a weighting number. Every character is converted to a value, multiplied by its weight, and the results are added up. That total is divided by 11, and the remainder is the check digit (a remainder of 10 is written as the letter X). If the digit you calculate matches the ninth character of the VIN, the VIN is internally consistent. If it does not match, the VIN has a typo or is not a genuine 17-character VIN.

How the year is read

Position 10 of the VIN encodes the model year. The letters and numbers used there repeat on a 30-year cycle, so the same code can mean, for example, 1995 or 2025. To tell them apart, this tool looks at position 7: on vehicles from 2010 onward it is a letter, while on 1980 to 2009 vehicles it is a number.

Methodology and sources

The check-digit math follows the U.S. federal VIN standard (Title 49 CFR Part 565) and ISO 3779. The letters I, O and Q are never used in a VIN because they look like 1 and 0. We do no lookups and store nothing; the calculation is pure arithmetic done on your device.

What this tool will not tell you

A valid check digit means the VIN is well-formed, not that the car exists or that the VIN belongs to a particular vehicle. To decode the full VIN into make, model and equipment, use our Ford VIN decoder. Some vehicles under 10,000 lb built before 1981 do not follow the modern 17-character standard, so this tool applies to 1981-and-newer VINs.