Calculate ISBN-10 and ISBN-13 check digits

When to check an ISBN

ISBN check digits use different rules depending on whether the number is ISBN-10 or ISBN-13. This calculator helps catch number errors before a book barcode or catalog record is prepared.

Check ISBNs before cover proofing

A wrong ISBN digit can follow a book through many files.

• Use the publisher supplied ISBN as the source.
• Check ISBN 10 and ISBN 13 only when both are needed.
• Compare the final barcode value with the cover metadata.

For books in distribution, the assigned number matters as much as the math.

Calculate or validate an ISBN

1. Enter 9 digits to calculate an ISBN-10 check digit.
2. Enter a full ISBN-10 or ISBN-13 to validate the existing check digit.
3. Compare the result with the publisher, catalog or book record.
4. Fix any typo before generating ISBN barcode artwork.
5. Check the printed barcode proof before approving a cover or catalog entry.

Where ISBN checks help

• Book covers
• Publishing proofs
• Catalog records

ISBN number checks

• ISBN-10 and ISBN-13 use different check digit rules.
• ISBN-10 check digits can be X, so do not remove it as if it were a typo.
• Use ISBN barcode generation after the identifier itself has been confirmed.

ISBN check digit mistakes to avoid

• Treating an ISBN check digit result as a new ISBN assignment.
• Removing an ISBN-10 X check digit because it doesn't look numeric.
• Copying an ISBN from an old draft instead of the final publisher record.

ISBN check digit questions