ISBN Validator & Converter
Check whether an ISBN is genuine and convert between the legacy 10-digit and current 13-digit formats. Paste the number with or without hyphens: the tool verifies the check digit, flags typos, converts ISBN-10 to its 978-prefixed ISBN-13 equivalent and back, and explains why 979-prefixed ISBNs can't be converted to ISBN-10. Handy for librarians, booksellers, publishers, and citation cleanup.
Converters
Private by default
This tool runs entirely in your browser. Your data is never uploaded to a server.
How to use
3 clear steps.
Paste the ISBN — 10 or 13 digits, hyphens optional.
The check digit is validated automatically.
Copy the converted ISBN-10 or ISBN-13 form.
Good to know
Frequently asked questions
- What's the difference between ISBN-10 and ISBN-13?
- ISBN-13 has been the standard since 2007: it's the old 10-digit number wrapped in the EAN barcode system with a 978 (or 979) prefix and a different check-digit formula. Every ISBN-10 has an ISBN-13 equivalent, but not the other way around.
- Why can't a 979 ISBN be converted to ISBN-10?
- The 10-digit system was only ever mapped to the 978 prefix. Books assigned 979 ISBNs (issued since the 978 space began filling up) simply have no 10-digit form.
- Does a valid check digit mean the book exists?
- No — it only proves the number is internally consistent. Whether it's assigned to a real book is a question for a bibliographic database like WorldCat or your national library.