ISBN Validator
Validate ISBN-10 and ISBN-13 checksums and convert ISBN-10 to ISBN-13.
Runs locally in your browser. Your input is not uploaded.
How to Use
- 1
Paste ISBNs
One per line — 10 or 13 digits, hyphens optional.
- 2
Read the verdicts
Checksums are verified and the ISBN type identified.
- 3
Grab conversions
Valid ISBN-10s include their ISBN-13 form.
Frequently Asked Questions
- ISBN-10 uses a weighted mod-11 checksum (with X representing 10); ISBN-13 uses the EAN mod-10 alternating 1/3 weights. Both are computed exactly, so any single-digit typo is caught.
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