ISBN-10 Validator

Verify ISBN-10 check digit.

Validate ISBN-10 check digit instantly. Free ISBN-10 validator for older books.

About ISBN-10

Verify ISBN-10 check digit.

ISBN-10 weights digits 10 down to 1; sum must be divisible by 11.

Where it is used

Older book cataloging, used-book apps.

How to use the ISBN-10

  1. ISBN-10 — enter the value (e.g. 0-306-40615-2).
  2. Calculate — press the Calculate button to see the result instantly above.

Formula

Weighted 10→1 sum mod 11; check digit X = 10.

Examples

Example

isbn:0-306-40615-2
Result: VALID ✓

Frequently Asked Questions

X check digit?
X represents the value 10 when the checksum needs it.
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