ISBN Validator

Validate a book number

An ISBN identifies a book, and it includes a check digit that catches typos. This tool validates ISBN-10 and ISBN-13 numbers by verifying the check digit, and can convert between the two formats.

How the check digit works

An ISBN’s last character is a check digit computed from the others by a weighted formula, so a single mistyped or transposed digit almost always makes the check fail. Validating an ISBN confirms it is well-formed and likely correct, which matters when handling book data where a typo would reference the wrong book or none. ISBN-10 and ISBN-13 use different check-digit schemes, and a book has both, so converting between them is useful when a system expects one and you have the other. The tool handles both formats and the conversion.

Correct book identifiers

It runs entirely in your browser, so nothing you paste is uploaded and the result is yours to copy straight into a project, which lets you work on private code and data without anything leaving your machine.

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