Firstly, find the numerical value associated with each letter in the VIN. (I, O and Q are not allowed.) Numerical digits use their own values.
A: 1
J: 1
B: 2
K: 2
S: 2
C: 3
L: 3
T: 3
D: 4
M: 4
U: 4
E: 5
N: 5
V: 5
F: 6
W: 6
G: 7
P: 7
X: 7
H: 8
Y: 8
R: 9
Z: 9
Secondly, look up the weight factor for each position in the VIN except the 9th (the position of the check digit).
1st: ×8
5th: ×4
10th: ×9
14th: ×5
2nd: ×7
6th: ×3
11th: ×8
15th: ×4
3rd: ×6
7th: ×2
12th: ×7
16th: ×3
4th: ×5
8th: ×10
13th: ×6
17th: ×2
Thirdly, multiply the numbers and the numerical values of the letters by their assigned weight factor, and sum the resulting products. Divide the sum of the products by 11. The remainder is the check digit. If the remainder is 10, the check digit is the letter X. Valid check digits also run through the numbers zero to 9.
Worked example
Consider the hypothetical VIN 1M8GDM9A_KP042788, where the underscore will be the check digit.
VIN:
1 M 8 G D M 9 A _ K P 0 4 2 7 8 8
Value:
1 4 8 7 4 4 9 1 0 2 7 0 4 2 7 8 8
Weight:
8 7 6 5 4 3 2 10 0 9 8 7 6 5 4 3 2
Products:
8 28 48 35 16 12 18 10 0 18 56 0 24 10 28 24 16
The sum of all 16 products is 351. Dividing by 11 gives a remainder of 10, so the check digit is "X" and the complete VIN is 1M8GDM9AXKP042788.
