📚 ISBN Validator
Validate ISBN-10 and ISBN-13 checksums, convert between formats, and identify the registration group (language/country) and GS1 prefix.
Structure breakdown
Type a valid ISBN to see how it splits into prefix, registration group, registrant, publication, and check digit.
Checksum calculation — step by step
Type a valid ISBN to see the weighted checksum calculation.
About this tool
Paste any ISBN (10 or 13 digits, with or without hyphens) and the tool verifies the checksum, identifies the format, and looks up the registration group to show the language or country the book was registered in. For ISBN-13 it also reports the GS1 prefix — 978 for the legacy book space and 979 for the newer allocation.
Use the Converted panel to flip an ISBN-10 into its ISBN-13 form (or vice-versa when the prefix is 978). For example, 0-306-40615-2 validates as an English-language ISBN-10 and converts to 978-0-306-40615-7; 978-2-07-036822-8 validates as a French-language ISBN-13 and converts back to 2-07-036822-8.
Handy for cataloguing a personal library, checking a barcode before listing a used book, cleaning up a spreadsheet of titles, or figuring out whether two editions of a book share the same underlying ISBN.
FAQ
What is the difference between ISBN-10 and ISBN-13? ›
ISBN-10 was the original 10-digit format used until 2006. Since 2007 books carry a 13-digit ISBN, which is the same number with a 978 prefix and a recomputed check digit. Most older books now have both: the ISBN-10 they were issued with, plus the derived ISBN-13.
Does a valid ISBN mean the book exists? ›
No. A valid ISBN passes its checksum and is structurally well-formed, but it does not guarantee the book was ever published, is in print, or that a particular copy is genuine. It only confirms the number itself is correctly formed.
Why does the X appear at the end of some ISBN-10s? ›
The ISBN-10 check digit can be 0 through 10, and a value of 10 is written as the Roman numeral X. This keeps every ISBN-10 exactly 10 characters. ISBN-13 never uses X — its check digit is always a single digit 0–9.
Can every ISBN-13 be converted to an ISBN-10? ›
Only ISBN-13s starting with 979 can NOT be converted back to a 10-digit form. The 979 prefix was opened in 2007 for books that never had an ISBN-10. ISBN-13s starting with 978 correspond one-to-one with an older ISBN-10 and can always be converted.
Is my ISBN sent anywhere? ›
No. All validation, conversion, and region lookup happen entirely in your browser. Nothing is uploaded.