VIN Tool

VIN Check Digit Calculator

The 9th character of a 17-character VIN is a check digit calculated from the other characters under the official formula in 49 CFR § 565.15. Enter a VIN below to calculate its check digit and confirm whether the VIN is mathematically valid.

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Enter a 17-character VIN

Last reviewed July 2026 · Formula per 49 CFR § 565.15

How the VIN check digit works

1. Transliterate — each letter is assigned a numeric value (see the table below); digits keep their own value.
2. Weight — multiply each character's value by its position weight.
3. Sum & divide by 11 — add the products and divide by 11. The remainder is the check digit; a remainder of 10 is written as X.

Character values (transliteration)

I, O, and Q are not used in VINs.

Letters	Value
A, 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
0–9	Digit's own value

Position weights

Position 9 (the check digit) has weight 0.

Position	Weight
1	8
2	7
3	6
4	5
5	4
6	3
7	2
8	10
9 (check digit)	0
10	9
11	8
12	7
13	6
14	5
15	4
16	3
17	2

Worked example

Take the VIN 1HGCM82633A004352. Assign each character its value, multiply by the position weight, and add the products. The total is 311. Dividing by 11 gives 28 remainder 3, so the check digit is 3 — which matches the 9th character of the VIN, so it is valid.

Official source

The VIN check-digit calculation — the position-9 rule, the character value table, the position weights, the divide-by-11 step, and the "remainder 10 = X" rule — is defined by U.S. federal regulation 49 CFR § 565.15, published in the Electronic Code of Federal Regulations by NHTSA.

Frequently asked questions

What is the 9th digit of a VIN?+

The 9th character of a 17-character VIN is the check digit. It is calculated from the other 16 characters and verifies whether the VIN was transcribed correctly.

How do I calculate a VIN check digit?+

Assign each VIN character its numeric value, multiply by the character's position weight, add the products, and divide the total by 11. The remainder is the check digit; if the remainder is 10, the check digit is the letter X. This formula is defined in 49 CFR § 565.15.

Are I, O, and Q allowed in VINs?+

No. Valid VINs use the letters A–Z except I, O, and Q, plus the digits 0–9. The letters I, O, and Q are excluded to avoid confusion with 1 and 0.

Does a valid check digit prove a VIN is real?+

No. A valid check digit only proves the VIN passes the mathematical check. A VIN can pass the check digit and still need to be verified against manufacturer or NHTSA records.

My VIN's check digit doesn't match. Is the VIN fake?+

Not necessarily. The check digit is required for vehicles built or sold in North America, but many vehicles built for other markets do not implement it. A mismatch can indicate a typo or a non-US VIN.