ISBN validator and converter
Helps publishers, librarians and booksellers confirm an ISBN before printing or listing, following the rules of ISO 2108.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter isbn.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
ISBN-10: the sum of each digit × its weight from 10 down to 1 is divisible by 11, with X worth 10. ISBN-13: weights alternate 1 and 3 and the sum is divisible by 10. Converting adds 978 and recomputes the check digit.
Example
Inputs: ISBN = 978-0-306-40615-7. Result: Result: Valid; Type: ISBN-13.
978-0-306-40615-7
7
Limits and caveats
- A correct check digit does not prove the book exists; that needs a publisher database.
- The tool does not insert official hyphens, since their positions depend on the group and publisher range tables.
Questions about this tool
Why do some ISBN-10s end in X?
The check digit is a remainder modulo 11, so it can equal 10, which is written as X.
Does every ISBN-13 have an ISBN-10 form?
Only those starting with 978. Numbers starting with 979 have no 10-digit equivalent.
Is the ISBN-13 the same as the EAN-13 barcode on the cover?
Yes, the number under a book barcode is the ISBN-13 itself, and its check digit is calculated the same way.