What is a VIN? The 17-character vehicle identification number, decoded
A Vehicle Identification Number — the VIN — is the 17-character serial that uniquely identifies every car, truck, and motorcycle built since 1981. This guide explains the structure character by character: the three sections, the math behind the check digit, the model-year codes, and how to run a free VIN check on any car listed at Copart or IAAI.
Try it: decode any 17-character VIN
Loading the interactive decoder — meanwhile, you can still paste a VIN into the form below.
What is a VIN?
A Vehicle Identification Number is the unique 17-character serial that every road-legal vehicle in North America has carried since 1981. The format was standardised that year by the National Highway Traffic Safety Administration (NHTSA), aligning with ISO 3779 and ISO 3780. Before 1981, manufacturers used their own VIN formats — some as short as 11 characters — which made cross-referencing recalls and titles a mess. The 17-character VIN solved that.
Every VIN uses uppercase letters A through Z and digits 0 through 9, with three exceptions: the letters I, O, and Q are never used because they look too much like 1 and 0. That leaves 33 valid characters at each position. The VIN is stamped or laser-etched onto the vehicle in several places — most visibly on a small plate at the base of the windshield on the driver's side dashboard, but also on the door jamb sticker, the engine block, the vehicle title, the registration, and your insurance card.
The VIN is what title agencies, insurers, and auction houses use to track a car across its lifetime. When a vehicle is sold at auction by Copart or IAAI, its VIN is the key that ties the listing back to the title, the damage report, and any previous accidents or recalls. That's why a quick VIN check can surface so much history with just 17 characters.
VIN structure: the three sections
The 17 characters split cleanly into three sections. Each section tells you something different about the vehicle: where it came from, what it is, and which specific unit on the production line it represents.
Positions 1-3: World Manufacturer Identifier (WMI)
The first three characters identify the country and manufacturer. Position 1 is the country of origin — 1, 4, and 5 are USA; 2 is Canada; 3 is Mexico; J is Japan; K is Korea; S is the United Kingdom; W is Germany. Position 2 is a manufacturer code assigned by SAE under NHTSA — so "1F" together means "Ford USA", "WBA" means "BMW AG", "JT" means "Toyota Japan". Position 3 identifies the vehicle type or division within the manufacturer (passenger car, truck, multipurpose vehicle, etc.).
Manufacturers that build fewer than 1,000 vehicles per year get a special WMI with "9" in position 3 plus three additional digits in positions 12-14 — so small coachbuilders and limited-run brands still get unique IDs.
Positions 4-9: Vehicle Descriptor Section (VDS)
The VDS encodes what the vehicle is. Positions 4 through 8 describe the body type, the chassis, the model line, the engine, and the restraint system — but the exact encoding is manufacturer-specific. Two different makers can use the same letter at position 5 to mean two completely different things. This is why a generic VIN decoder needs a make-specific lookup table for every brand it supports.
Position 9 is the check digit — the most mathematically interesting character in the VIN. It is computed from the other 16 characters using a weighted-sum algorithm (more on that below). The check digit is 0 through 9, or the letter X to represent the value 10. If you change any single character elsewhere in the VIN, the check digit will no longer match — so it's the first thing automated systems verify when they ingest a VIN.
Positions 10-17: Vehicle Identifier Section (VIS)
The VIS identifies the specific unit. Position 10 is the model year code (see the table below). Position 11 is the assembly plant — every Ford F-150 built in Dearborn shares the same plant code; every one built in Kansas City shares a different one. Positions 12 through 17 are the production sequence — a six-character serial number that uniquely identifies this exact vehicle on the assembly line. The very first 2024 Tesla Model 3 off the Fremont line and the very last one share every character except those last six.
Model year codes (position 10)
The model year cycles through a 30-character alphabet (skipping I, O, Q, U and Z because of visual ambiguity, and Z because the cycle restarts with 1). Here is the lookup table for the years vinfax currently archives:
| Year | Code | Year | Code | Year | Code |
|---|---|---|---|---|---|
| 2008 | 8 | 2018 | J | 2028 | W |
| 2009 | 9 | 2019 | K | 2029 | X |
| 2010 | A | 2020 | L | 2030 | Y |
| 2011 | B | 2021 | M | — | — |
| 2012 | C | 2022 | N | — | — |
| 2013 | D | 2023 | P | — | — |
| 2014 | E | 2024 | R | — | — |
| 2015 | F | 2025 | S | — | — |
| 2016 | G | 2026 | T | — | — |
| 2017 | H | 2027 | V | — | — |
A subtle gotcha: the year code is the model year, not the calendar year of manufacture. A 2024 Toyota Camry built in October 2023 will still have an R at position 10 — manufacturers commonly start producing next year's models a few months before the calendar flips.
Why we drop I, O and Q
Three letters are blacklisted from every VIN: I (looks like 1), O (looks like 0), and Q (looks like O, which looks like 0). The standard skips them so a smudged tow sheet or a hand-typed registration form can't garble a VIN. The model-year encoding also skips U and Z for similar reasons, and because the alphabet wraps back to numbers after Y. If a VIN check tool ever accepts an I, O or Q in your input, it has a bug — and you should not trust its output.
How to validate a VIN: the check digit
Position 9 is the VIN's built-in self-check. The algorithm assigns each character a numeric value (digits are themselves; A=1, B=2, C=3, D=4, E=5, F=6, G=7, H=8, J=1, K=2, L=3, M=4, N=5, P=7, R=9, S=2, T=3, U=4, V=5, W=6, X=7, Y=8, Z=9 — note the irregular gaps where I, O and Q would be). Each position then has a fixed weight: 8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2 — the weight at position 9 is 0, which makes the check digit "transparent" to itself.
Multiply each character's value by its position weight, sum the results, divide by 11, and take the remainder. That remainder is the expected check digit; if the remainder is 10, the check digit is written as X. Any single character substitution or transposition will break the math, which is why insurance back-office systems can sanity-check a VIN before they even look it up. For an interactive walk-through with worked examples, see our dedicated VIN decoder page.
Where to find your VIN
On the vehicle itself the VIN appears in several places, partly so it's hard to forge a clean title by swapping plates. The most common locations:
- Dashboard — a small metal plate visible through the windshield on the driver's side, where the dash meets the glass.
- Driver's door jamb — on the sticker that also lists tyre pressures and the date of manufacture.
- Engine block or firewall — stamped into the metal; useful when investigating a possibly cloned VIN.
- Vehicle title and the registration document.
- Insurance card or policy declarations.
- Service history book, especially on European cars.
If the dashboard plate and the door jamb sticker disagree, that's a serious red flag — it suggests the car has been re-VINed, often after a salvage rebuild. A salvage title in itself is not fraudulent, but a mismatched VIN is.
Run a free VIN check on vinfax
vinfax indexes every Copart and IAAI listing since 2024 — over a million vehicles and counting. Paste a 17-character VIN into our free VIN check and you'll get the auction history, damage codes, photos, sale dates, and lot numbers for every appearance on either auction. No signup, no paywall. If you're researching specific damage types or looking at current inventory, our archive is the most thorough public source we know of.
Related guides
Now that you understand the structure, you can dig deeper: the full VIN decoder math, what salvage titles mean, and how Copart and IAAI differ as data sources.