๐ ISBN Validator & Converter
Validates the check digit of an entered ISBN (International Standard Book Number) and converts between ISBN-10 and ISBN-13 formats. Hyphens and spaces in the input are handled automatically.
How to use
- Enter an ISBN-10 (10 digits) or ISBN-13 (13 digits), with or without hyphens.
- The check digit is validated automatically.
- If valid, the equivalent in the other format (10-digit โ 13-digit) is shown as well.
How the calculation works
The ISBN (International Standard Book Number) identifies books. It comes in a 10-digit ISBN-10 and, since 2007, a 13-digit ISBN-13. In both, the last digit is a check digit that catches typing mistakes. ISBN-10: multiply the digits by weights 10, 9, 8 โฆ 1 and add them up; the number is valid if the total is divisible by 11. A check digit of 10 is written "X". ISBN-13: multiply the digits alternately by 1 and 3 and add them up; the number is valid if the total is divisible by 10. The tool removes hyphens and spaces, identifies the format by length and checks the check digit. For valid numbers it also shows the ISBN-10/ISBN-13 conversion (to get an ISBN-13, it adds the 978 prefix and recalculates the check digit).
Worked example
ISBN-10: 0-306-40615-2 0ร10 + 3ร9 + 0ร8 + 6ร7 + 4ร6 + 0ร5 + 6ร4 + 1ร3 + 5ร2 + 2ร1 = 132 132 รท 11 = 12 (divisible) โ valid As ISBN-13: 978-0-306-40615-7 Changing the last digit to 978-0-306-40615-8 gives a total not divisible by 10, so it is invalid.
Things to be aware of
- ISBN-13s starting with 979 have no ISBN-10 equivalent.
- The check digit catches typing mistakes; it cannot tell you whether a book with that number was actually published.
- Almost all books published in Japan have ISBN-13s starting 978-4- (4 is the Japanese-language group).
FAQ
What's the difference between ISBN-10 and ISBN-13?
ISBN-13 is the successor to ISBN-10, extended to 13 digits for compatibility with the EAN barcode standard. Books published since 2007 generally use ISBN-13.
Can every ISBN-13 be converted to ISBN-10?
No. Only ISBN-13s starting with the "978" prefix have a corresponding ISBN-10. ISBN-13s starting with "979" have no ISBN-10 equivalent.
How is the check digit calculated?
ISBN-10 validity requires the sum of each digit times a weight from 10 down to 1 to be a multiple of 11 (the last digit can be 0-9 or 'X' representing 10). ISBN-13 uses the same scheme as EAN-13: alternating weights of 1 and 3, with the total required to be a multiple of 10.