VIN Format Explained
A modern VIN is 17 characters long and divides into four sections. Each section has a defined job under 49 CFR 565.15, the U.S. content rules for VINs. This page covers the layout, the arithmetic behind the check digit, how the model-year code works, and where the layout stops applying. For the plain definition of a VIN, start with what is a VIN. |
The four sections
| Positions | Section | What the regulation assigns to it |
|---|---|---|
| 1 to 3 | Manufacturer identifier | Identifies the manufacturer and type of vehicle. For low-volume manufacturers, positions 12 to 14 also form part of the identifier. |
| 4 to 8 | Vehicle description | Attributes of the vehicle, coded by the manufacturer. For passenger cars these include make, line, series, body type and engine type. |
| 9 | Check digit | A calculated character, 0 to 9 or the letter X, used to verify that the VIN was transcribed correctly. |
| 10 to 17 | Vehicle identification | Position 10 is the model year, position 11 identifies the plant, and the remaining positions form the production sequence. |
Only the digits 0 to 9 and the letters A to Z except I, O and Q are permitted. Excluding those three letters keeps them from being confused with 1 and 0 (49 CFR 565.13).
Positions 1 to 3: the manufacturer identifier
The first character generally points to a country or region of manufacture, and the next two narrow it to a manufacturer. A manufacturer can hold more than one identifier, for example for different divisions or vehicle types. If a manufacturer identifier needs six characters, a 9 is placed in the third position and the other three sit at positions 12 to 14.
Positions 4 to 8: the vehicle description
The regulation says what must be described. It leaves the code to the manufacturer. A character in position 5 may mean an engine to one maker and a body style to another, so there is no universal table for these five characters. Decoding them correctly requires each manufacturer’s own tables, and that is where decoders differ most in depth and detail.
Position 9: the check digit
The check digit is calculated after the other 16 characters are fixed. The method:
- Replace each letter with a number using the standard conversion. Digits keep their value.
- Multiply each value by the weight for its position.
- Add the products and divide the total by 11.
- The remainder is the check digit. A remainder of 10 is written as X.
Letter values: A and J = 1; B, K, S = 2; C, L, T = 3; D, M, U = 4; E, N, V = 5; F, W = 6; G, P, X = 7; H, Y = 8; R, Z = 9.
Position weights, positions 1 to 17: 8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2. Position 9 has weight 0, because that is where the result goes.
Worked example. The regulation publishes a sample calculation whose character values, written as digits, give the string 17418598?57118341, with the check digit position left open. The products by position are 8, 49, 24, 5, 32, 15, 18, 80, 0, 45, 56, 7, 6, 40, 12, 12 and 2. They add to 411. Dividing 411 by 11 gives 37 with a remainder of 4, so the check digit is 4. This string is an arithmetic illustration taken from the rule, not the VIN of any particular vehicle.
What the check digit can and cannot catch. Every position weight except position 9’s is non-zero in this arithmetic, so a single wrong character that changes the value is always caught. Swapping two adjacent characters is caught unless they have the same value. Two limits matter in practice. Letters that share a value, such as A and J, can be substituted for one another without changing the result. And a VIN with several errors can pass by chance: for a random wrong string the chance of still matching is about one in eleven. A correct check digit shows that the VIN is internally consistent. It does not show that the number belongs to the vehicle you are looking at.
The check digit is required on vehicles built to U.S. rules. In many European-market VINs the ninth character is not this check digit, so a failed check on such a vehicle is not by itself proof of an error.
Positions 10 to 17: model year, plant, sequence
Position 10 holds a model-year code. The letters run A to Y while skipping I, O, Q, U and Z, then the digits 1 to 9 take over, so the cycle repeats every 30 years. For passenger cars and for multipurpose passenger vehicles and trucks of 10,000 lb gross vehicle weight rating or less, position 7 settles which cycle applies: if it is numeric the year falls in 1980 to 2009, and if it is alphabetic the year falls in 2010 to 2039.
Codes for the current cycle (2010 to 2039); subtract 30 years for the earlier cycle:
- A 2010 · B 2011 · C 2012 · D 2013 · E 2014 · F 2015 · G 2016 · H 2017 · J 2018 · K 2019
- L 2020 · M 2021 · N 2022 · P 2023 · R 2024 · S 2025 · T 2026 · V 2027 · W 2028 · X 2029
- Y 2030 · 1 2031 · 2 2032 · 3 2033 · 4 2034 · 5 2035 · 6 2036 · 7 2037 · 8 2038 · 9 2039
The code is the model year the manufacturer designates, which is not always the calendar year the vehicle was built. A vehicle assembled late in one calendar year can carry the next year’s code.
Position 11 identifies the assembly plant, using the manufacturer’s own plant codes. Positions 12 to 17 are the production sequence, which makes the VIN specific to one vehicle.
Where the layout does not apply
| Vehicle or era | What to expect |
|---|---|
| Built to current U.S. rules (2009 and later) | 17 characters, check digit in position 9, model-year code in position 10. |
| Model year 2009 or earlier | Covered by alternative requirements under the same regulation. The 17-character format has been the norm since the 1981 model year. |
| Before 1981 | Length and meaning varied by manufacturer. Decoding depends on manufacturer-specific records, and classic-vehicle data may be incomplete. |
| Motorcycles, trailers, RVs, ATVs | Often follow the same format but can differ in marking location and available data. |
| Built for other markets | Different regional standards apply. The check digit and the model-year convention may not follow the U.S. pattern. |
The ability to process an identifier does not mean every field or record type exists for it. Coverage depends on the vehicle, its era, and the identifier. See coverage and data availability for how that varies.
Why a VIN fails to return a result
- The letter O or I was typed instead of 0 or 1. Neither letter can appear in a VIN.
- A character was misread from a worn label, glare or a photo.
- The VIN is shorter or longer than 17 characters because the vehicle is older or built to another standard.
- The VIN is valid but the sources searched hold nothing for it.
The last case is different from the others and is covered in why vehicle data may be missing or incorrect.
From layout to decoded information
Knowing the layout tells you what each section means. Getting the actual make, model, engine and plant for a specific VIN is what the VIN Decoder does. Decoding identifies the vehicle and its specifications. It does not show accident, title or ownership history.
Sources and basis
- 49 CFR 565.15, Content requirements: the four sections, check-digit weights and sample calculation, year codes and the position 7 rule
- 49 CFR 565.13, General requirements: 17 characters and the permitted character set
- Letter values and the one-in-eleven figure: the first comes from the standard conversion table in the regulation; the second is arithmetic (11 possible remainders), stated here as approximate.
