Validate ISBN
Enter an ISBN-10 or ISBN-13 with optional spaces or hyphens to verify its check digit.
A QUICK WALKTHROUGH
How to use this tool
- Enter one ISBN-10 or ISBN-13.
- Spaces and hyphens are removed; mixed characters are rejected.
- Review the format and normalized ISBN result.
What is checked
ISBN-10 uses the modulus-11 check with a final X representing 10. ISBN-13 uses alternating weights of 1 and 3. Spaces and hyphens are accepted; other characters are rejected.
Scope
A valid format and check digit show mathematical consistency only. They do not confirm that a book record exists, that an ISBN was assigned, or that a publication is active. Processing stays in your browser.
GOOD TO KNOW
Common questions
Can ISBN-10 end with X?
Yes. A final uppercase or lowercase X represents the ISBN-10 value 10.
Does this look up books?
No. This tool performs format and check-digit validation only.