VIN check digit algorithm

Client

The VIN check digit algorithm uses fixed position weights and letter transliteration—not Luhn mod-10. Paste a frame to see pass/fail and expected ninth symbol while learning the published weight table.

Weight table overview

Weights 8,7,6,5,4,3,2,10,0,9,8,7,6,5,4,3,2 multiply transliterated values. Remainder mod 11 maps to the check symbol—with X when the remainder is ten.

Privacy: parsing runs only in your browser. This page does not query DMV, insurance, or manufacturer databases—only the published mod-11 rule for the ninth character.
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After removing spaces and hyphens, the frame must be exactly 17 characters. Letters I, O, and Q are forbidden everywhere. Position 9 (index 8) is the check symbol: decimal 0–9 or X for remainder ten. Each symbol maps to a numeric value, is multiplied by a fixed weight for its position, products are summed, and sum mod 11 must equal the check symbol’s value (X → 10).

Result

Passes check digit — weighted sum mod 11 is 10; expected X.

  • WMI (positions 1–3): 1HG
  • Attributes (4–8): BH41J
  • Check (9): X
  • Model year code (10): M
  • Plant (11): N
  • Sequential (12–17): 109186

Common use cases

  • Document mod-11 for engineering QA specs.
  • Contrast VIN mod-11 with IMEI Luhn in mixed identifier training.
  • Verify algorithm implementations against a reference page.

Common mistakes to avoid

  • Using Luhn doubling on VIN strings

    VIN uses weighted products summed mod 11—different from payment-card Luhn.

  • Including position nine in the weighted sum

    Position nine weight is zero—the check symbol compares to the remainder.

FAQ

What algorithm does VIN use?

ISO 3779 transliteration, fixed weights, sum mod 11, compare to position nine (0–9 or X).

Is VIN check digit Luhn?

No—VIN uses mod-11 weighted sum; IMEI and cards use Luhn mod-10.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • vin check digit verifier online
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