ISBN Validator
Check an ISBN-10 or ISBN-13 checksum after removing hyphens and spaces.
This tool runs entirely in your browser. Your files are never uploaded to a server.
Valid: Valid ISBN-13.
- Format: ISBN-13
- Prefix: 978
9780306406157Clear the entered value before starting another check. Validation runs locally and does not check against any external registry, server, or account.
What this tool does
Checks whether a 10- or 13-character value is a valid ISBN by removing hyphens and spaces and verifying its checksum digit.
How to use it
Enter an ISBN with or without hyphens. Based on the cleaned length, the checker applies the ISBN-10 modulus-11 weighting or the ISBN-13 modulus-10 weighting and reports whether the checksum matches.
Example
Entering 978-0-306-40615-7 returns valid as an ISBN-13 with the Bookland prefix 978, while 0-306-40615-2 returns valid as the equivalent ISBN-10.
Validation
An ISBN-10 must be nine digits plus a final digit or X, with the weighted sum (digit × position 10 down to 1, X counted as 10) divisible by 11; an ISBN-13 must be 13 digits starting with 978 or 979, with the alternating 1-3 weighted sum divisible by 10.
How to interpret the result
A valid result confirms the checksum is mathematically correct for a real or hypothetical ISBN — it does not confirm the number is registered to an actual published book.
Limitations
This checker validates checksum arithmetic only; it does not look up title, author, publisher or availability, and does not convert between ISBN-10 and ISBN-13 (both are checked independently by length).
Privacy
All processing uses local browser APIs and this tool does not upload the values you enter.
Frequently Asked Questions
- What does ISBN Validator do?
- Checks whether a 10- or 13-character value is a valid ISBN by removing hyphens and spaces and verifying its checksum digit.
- How does it handle invalid input?
- An ISBN-10 must be nine digits plus a final digit or X, with the weighted sum (digit × position 10 down to 1, X counted as 10) divisible by 11; an ISBN-13 must be 13 digits starting with 978 or 979, with the alternating 1-3 weighted sum divisible by 10.
- Is entered data uploaded?
- All processing uses local browser APIs and this tool does not upload the values you enter.
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