Position-by-position explanation
- 1 — Country / Region code
Identifies the vehicle's country of manufacture (e.g., 1/4/5 = USA, J = Japan, W = Germany). - 2 — Manufacturer code (part of WMI)
With position 1 and 3, completes the World Manufacturer Identifier. - 3 — Manufacturer code (part of WMI)
- 4 — Vehicle attributes
Manufacturer-defined: body style, restraint system, model series, etc. - 5 — Engine or powertrain code
- 6 — Transmission / braking / additional attributes
- 7 — Vehicle feature / option group
- 8 — Vehicle feature / option group
- 9 — Check digit
A calculated value used to validate the VIN's integrity. Can be 0–9 or 'X' (for value 10). - 10 — Model year code
A single digit or letter that indicates model year (cycles roughly every 30 years). - 11 — Plant / assembly code
- 12–17 — Serial number
Manufacturer-assigned production sequence number (unique per vehicle).
How the check digit (position 9) is calculated
The standard VIN check-digit algorithm (ISO/SAE) works like this:
- Transliterate each VIN character to a numeric value (0–9). Digits stay the same; letters map to numbers via a standard table.
- Apply weights for each VIN position:
8,7,6,5,4,3,2,10,0,9,8,7,6,5,4,3,2(position 9 weight = 0). - Multiply each transliterated value by its position weight and sum the results.
- Take sum mod 11. If remainder is 10, the check digit is
X. Otherwise it is the numeric remainder (0–9).
Transliteration table (letters → numbers)
{
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
}
Position weights
[8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2]
Practical tips & edge cases
- Always cross-check VIN from two or more locations (windshield, door jamb, title) to detect tampering.
- Model year ambiguity: the 10th character cycles every ~30 years — combine with registration or build data to determine actual year.
- Characters I, O, Q: commonly omitted to avoid confusion with 1 and 0.
- Non-standard / older vehicles: pre-1981 VINs may be shorter and use different schemes.
Small check-digit validator (try your VIN)
Enter a 17-character VIN to validate its check digit (position 9). This runs the standard algorithm.
FAQ
Can VIN letters include I, O or Q?
Characters I, O and Q are typically not used in VINs to avoid confusion with numbers 1 and 0. If you see them, treat the VIN as non-standard and verify carefully.
Does the 10th character uniquely identify the vehicle year?
The 10th character indicates model year, but it cycles roughly every 30 years. Use registration records or manufacturing data to disambiguate the exact year.
What if the check digit does not match?
A mismatched check digit may indicate a transcription error or tampering. Do not rely on that VIN alone when buying — ask for a professional inspection or check other VIN locations and documents.