ISBN checker

Validate an ISBN-10 or ISBN-13 check digit and convert between the two formats.

Checked in this browser. Nothing is sent anywhere.

Accepts 10- or 13-digit ISBNs with or without hyphens; X is allowed as the last ISBN-10 character. The check digit is recomputed, so a mistyped digit is flagged. Conversion between the two formats keeps the same book identifier.

How to use

  1. Enter an ISBN with or without hyphens.
  2. See whether the check digit is correct.
  3. Copy the normalized digits or the converted form.

What it supports

Accepts 10 digits (the last may be X) or 13 digits; hyphens and spaces are ignored. An ISBN-13 converts to ISBN-10 only when it starts with 978. The check digit is recomputed, so a mistyped digit is caught — but a valid number is not proof a book with that ISBN exists.

Related tools

Related guides