ISBN Validator & Check Digit — Free Online Tool

Validate ISBN-10 and ISBN-13 book numbers and compute their check digits. ISBN Validator & Check Digit is a free online tool from the ToolsRift Hash & Crypto Tools collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.

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How to use ISBN Validator & Check Digit

  1. Open the ISBN Validator & Check Digit above — it loads instantly, no account needed.
  2. Enter or upload your input. Everything is processed locally on your device.
  3. Get your result immediately and copy or download it with one click.

Frequently asked questions

What is an ISBN check digit?

The last digit of an ISBN is a checksum. ISBN-10 uses a weighted mod-11 sum (with 'X' meaning 10); ISBN-13 uses an alternating 1/3 weighted mod-10 sum.

Can this convert ISBN-10 to ISBN-13?

This tool validates and computes check digits. An ISBN-10 becomes ISBN-13 by prefixing '978' and recomputing the final check digit, which the ISBN-13 mode will do for you.

Are hyphens required?

No — hyphens and spaces are ignored. Only the digits (and a trailing X for ISBN-10) are used in the calculation.

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