ISBN Validator
Check whether an ISBN-10 or ISBN-13 passes its checksum, ignoring hyphens and spaces.
Quick answer: enter your details below and click Validate — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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How to use
- Type the ISBN, with or without hyphens.
- Click Validate.
- Read which form was found and whether its checksum passes.
About this tool
Type an ISBN with or without hyphens and this tool strips the separators, works out whether it is the 10-character or 13-digit form, and runs the matching checksum. It tells you which form it found and whether the checksum passes. A passing checksum means the digits are consistent, not that the book is in any particular catalogue.
Frequently asked questions
Why is X allowed at the end of an ISBN-10?
Because the ISBN-10 checksum works modulo 11, the value 10 is needed as a possible check value, and it is written as X.
Does a valid ISBN prove the book exists?
No. It only proves the digits satisfy the checksum rule; a made-up number can pass while naming no real book.