Vehicle identification number

VIN: classification

There are at least four competing standards used to calculate the VIN.

Components

Modern VINs are based on two related standards, originally issued by the International Organization for Standardization (ISO) in 1979 and 1980: ISO 3779 and ISO 3780, respectively. Compatible but different implementations of these ISO standards have been adopted by the European Union and the United States, respectively.

The VIN comprises the following sections:

World manufacturer identifier

The first three characters uniquely identify the manufacturer of the vehicle using the world manufacturer identifier or WMI code. A manufacturer who builds fewer than 2000 vehicles per year uses a 9 as the third digit, and the 12th, 13th and 14th position of the VIN for a second part of the identification. Some manufacturers use the third character as a code for a vehicle category (e.g., bus or truck), a division within a manufacturer, or both. For example, within 1G (assigned to General Motors in the United States), 1G1 represents Chevrolet passenger cars; 1G2, Pontiac passenger cars; and 1GC, Chevrolet trucks.

The Society of Automotive Engineers (SAE) in the U.S. assigns WMIs to countries and manufacturers.

The first character of the WMI is the region in which the manufacturer is located. In practice, each is assigned to a country of manufacture, although in Europe the country where the continental headquarters is located can assign the WMI to all vehicles produced in that region (Example: Opel/Vauxhall cars whether produced in Germany, Spain, the United Kingdom or Poland carry the W0L WMI because Adam Opel AG is based in Rüsselsheim, Germany).

In the notation below, assume that letters precede numbers and that zero is the last number. For example, 8X–82 denotes the range 8X, 8Y, 8Z, 81, 82, excluding 80.

Vehicle descriptor section

The fourth to eighth positions in the VIN are the vehicle descriptor section or VDS. This is used, according to local regulations, to identify the vehicle type, and may include information on the automobile platform used, the model, and the body style. Each manufacturer has a unique system for using this field. Most manufacturers since the 1980s have used the eighth digit to identify the engine type whenever there is more than one engine choice for the vehicle. Example: for the 2007 Chevrolet Corvette, U is for a 6.0L V8 engine, and E is for a 7.0L V8.

North American check digits

One element that is fairly consistent is the use of position nine as a check digit, compulsory for vehicles in North America, and used fairly consistently elsewhere.

Vehicle identifier section

The 10th to 17th positions are used as the 'vehicle identifier section' (VIS). This is used by the manufacturer to identify the individual vehicle in question. This may include information on options installed or engine and transmission choices, but often is a simple sequential number. In North America, the last five digits must be numeric.

Model year encoding

One consistent element of the VIS is the 10th digit, which is required worldwide to encode the model year of the vehicle. Besides the three letters that are not allowed in the VIN itself (I, O and Q), the letters U and Z and the digit 0 are not used for the model year code. The year code is the model year for the vehicle.

The year 1980 was encoded by some manufacturers, especially General Motors and Chrysler, as "A" (since the 17-digit VIN was not mandatory until 1981, and the "A" or zero was in the manufacturer's pre-1981 placement in the VIN), yet Ford and AMC still used a zero for 1980. Subsequent years increment through the allowed letters, so that "Y" represents the year 2000. 2001 to 2009 are encoded as the digits 1 to 9, and subsequent years are encoded as "A", "B", "C", etc.

On April 30, 2008, the US National Highway Traffic Safety Administration adopted a final rule amending 49 CFR Part 565, "so that the current 17 character vehicle identification number (VIN) system, which has been in place for almost 30 years, can continue in use for at least another 30 years", in the process making several changes to the VIN requirements applicable to all motor vehicles manufactured for sale in the United States. There are three notable changes to the VIN structure that affect VIN deciphering systems:

Plant code

Compulsory in North America, is the use of the 11th character to identify the factory at which the vehicle was built. Each manufacturer has its own set of plant codes.

Production number

In the United States, the 12th to 17th digits are the vehicle's serial or production number. This is unique to each vehicle, and every manufacturer uses its own sequence.

Check-digit calculation

Check-digit validation is compulsory for all road vehicles sold in North America.

When trying to validate a VIN with a check digit, first either (a) remove the check digit for the purpose of calculation or (b) use a weight of zero (see below) to cancel it out. The original value of the check digit is then compared with the calculated value. If the calculated value is 0–9, the check digit must match the calculated value. If the calculated value is 10, the check digit must be X. If the two values do not match (and there was no error in the calculation), then there is a mistake in the VIN. However, a match does not prove the VIN is correct, because there is still a 1/11 chance that any two distinct VINs have a matching check digit: for example, the valid VINs 5GZCZ43D13S812715 (correct with leading five) and SGZCZ43D13S812715 (incorrect with leading character "S"). The VINs in the Porsche image, WP0ZZZ99ZTS392124, and the GM-T body image, KLATF08Y1VB363636, do not pass the North American check-digit verification.

Transliterating the numbers

Transliteration consists of removing all of the letters, and substituting them with their appropriate numerical counterparts. These numerical alternatives (based on IBM's EBCDIC) are in the following chart. I, O, and Q are not allowed in a valid VIN; for this chart, they have been filled in with N/A (not applicable). Numerical digits use their own values.

S is 2, and not 1. There is no left-alignment linearity.

Weights used in calculation

The following is the weight factor for each position in the VIN. The 9th position is that of the check digit. It has been substituted with a 0, which will cancel it out in the multiplication step.

Worked example

Consider the hypothetical VIN 1M8GDM9A_KP042788, where the underscore will be the check digit.

1. The VIN's value is calculated from the above transliteration table. This number is used in the rest of the calculation.
2. Copy the weights from the above Weight Factor Table.
3. The products row is the result of the multiplication of the vertical columns: Value and Weight.
4. The products (8, 28, 48, 35 ... 24, 16) are all added together to yield a sum, 351.
5. Find the remainder after dividing by 11
   351 MOD 11 = 10
   351 ÷ 11 = 31 ¹⁰/₁₁
6. The remainder is the check digit. If the remainder is 10, the check digit is X. In this example, the remainder is 10, so the check digit is transliterated as X.

With a check digit of X, the VIN 1M8GDM9A_KP042788 is written 1M8GDM9AXKP042788.

A VIN with Straight-ones (seventeen consecutive 1s) has the nice feature that its check digit 1 matches the calculated value 1. This is because a value of one multiplied by 89 (sum of weights) is 89, and 89 divided by 11 is 8 with remainder  ¹⁄₁₁; thus 1 is the check digit. This is a way to test a VIN-check algorithm.

VIN scanning

VINs may be optically read with barcode scanners or digital cameras, or digitally read via OBD-II in newer vehicles. There are smartphone applications that can pass the VIN to websites to decode the VIN.

List of common WMI

The Society of Automotive Engineers (SAE) assigns the WMI (world manufacturer identifier) to countries and manufacturers. The following list shows a small selection of world manufacturer codes.