Reading the model year from a VIN

The tenth character of a VIN encodes the model year. It is a single letter or digit from a cycle of 30, so every character stands for two possible years, 30 years apart: A is 1980 or 2010, Y is 2000 or 2030, and 9 is 2009 or 2039. Position 7 and the vehicle itself usually settle which one.

The 30 characters

The cycle uses the letters A to Y without I, O, Q, U and Z, followed by the digits 1 to 9. The digit 0 is never used, which matches NHTSA's own decoder: it flags a position 10 that holds I, O, Q, U, Z or 0 as an incorrect model year.

Choosing between the two years

For passenger cars, multipurpose passenger vehicles and trucks with a gross vehicle weight rating of 10,000 lb or less, the regulation uses position 7 as a switch. A letter there means the later cycle, 2010 to 2039; a digit means the earlier one, 1980 to 2009. Heavier trucks, buses, trailers and motorcycles do not follow this rule, so for them the age of the vehicle has to decide.

A second clue comes from the manufacturer code. Each code's decoding rules cover a known span of model years, and when one of the two candidates falls outside that span, it can be ruled out. The VIN checker applies both clues.

How many codes cover each model year

Counting the three-character codes whose decoding rules include a given model year shows how the catalog has grown. Model year 1981 is covered by 300 codes, 2000 by 1,183 and 2010 by 1,679. The count keeps rising to 2,414 for 2027, the highest of any year, because most codes have rules with no end year.

Not every code stays active. Of the codes with decoding rules, 721 have rules that stop at a fixed year, and 368 of those stop before 2010. For a VIN from one of these codes, the later candidate year can be dropped. A typical case is VF1, whose rules end with model year 1989.

Model year is not the build date

The model year is the manufacturer's designation, not the date of manufacture, and the two do not have to match: a VIN with a 2027 character can belong to a vehicle assembled in 2026. The month and year of manufacture appear on the vehicle's certification label, not in the VIN.

Common misreadings

Two misreadings are easy to make. The first is reading position 10 from the wrong end, or counting the check digit as the year. The second is assuming the earlier cycle for a recent vehicle: an A on a 2010 car does not mean 1980. Position 7 settles it for most light vehicles. If the VIN has fewer than 17 characters, it predates the current system and none of this applies.

When codes stop

Closed rule sets cluster in time: more end in the 2000s than in any other decade, 248 codes. A closed code is useful when reading position 10. If its rules end before 2010, a VIN carrying it cannot be from the later cycle, and the checker says which of the two candidate years the rules cover.

A worked example

Take 1HGCV1F31LA000000, the example used by the VIN checker. Position 10 is L, so the model year is 1990 or 2020. Position 7 is the letter F, which for a light vehicle points to the later cycle, 2020. The code 1HG is registered for passenger cars, so the position 7 rule applies, and its decoding rules start in 1981 and have no end year, which fits either year on their own. Here position 7 is the deciding clue.

The position 7 rule covers a minority of codes. Passenger cars, multipurpose passenger vehicles and trucks account for 677 of the 3,163 three-character codes, 21 percent, and the weight limit narrows the trucks further. For trailers, motorcycles and buses the age of the vehicle, or a closed rule span, has to settle the year.

The rules also show a few codes reaching back to model year 1980: 43 codes have rules that start there, one year before the bulk of the catalog begins in 1981.