ISBN Validator & Converter
Validate ISBN-10 or ISBN-13 and convert between the two formats.
Validate and convert ISBNs
Every published book carries an ISBN with a built-in check digit, and there are two formats: the older 10-digit and the current 13-digit. This tool validates either and converts between them.
0-306-40615-2 is a valid ISBN-10 that converts to 978-0-306-40615-7 as an ISBN-13. Hyphens are ignored, so you can paste the number however it is printed on the book.
Accurate and private
It applies the mod-11 check for ISBN-10 and the mod-10 check for ISBN-13, and runs entirely in your browser with nothing uploaded.
Frequently Asked Questions
How are ISBNs validated?
ISBN-10 uses a mod-11 weighted checksum (with X meaning 10); ISBN-13 uses the same mod-10 scheme as EAN barcodes. The tool checks whichever length you enter.
Can it convert between formats?
Yes. A 10-digit ISBN converts to 13 by prefixing 978 and recomputing the check digit, and a 978-prefixed 13 converts back to 10.
Does it accept hyphens?
Yes — hyphens and spaces are ignored, so you can paste an ISBN in any common grouping.
Browse the full set of free, private, in-browser tools.