ISBN Validator

Quickly verify the accuracy of ISBN-10 and ISBN-13 numbers. Our free tool checks the mathematical checksum to ensure your book identifiers are valid and error-free.

Why Validate ISBN Numbers?

The International Standard Book Number (ISBN) is a unique commercial book identifier barcode. Whether you are a bookseller, librarian, or self-publishing author, data accuracy is paramount. A single digit error in an ISBN can lead to lost sales, inventory mismatches, and listing failures on platforms like Amazon and Goodreads. Our ISBN Validator eliminates guesswork by running the official checksum algorithm on your input.


This free tool supports both the older 10-digit standard and the modern 13-digit format (which matches the EAN-13 barcode). It intelligently ignores hyphens and spaces, allowing you to validate numbers directly from book covers or inventory spreadsheets without manual formatting. By ensuring your ISBNs are mathematically valid, you protect your professional reputation and streamline the distribution process.


Use this utility to double-check data entry, convert legacy lists to the 13-digit standard, or simply verify a book's identity before purchase. No installation or account is required—just secure, instant validation in your browser with No Tools Left Behind.

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Examples

Valid ISBN-10 Valid

0-306-40615-2

Input: A standard formatted ISBN-10.

Result: Checksum passes. This is a known valid code.

Valid ISBN-13 Valid

978-3-16-148410-0

Input: A standard formatted ISBN-13.

Result: Checksum passes. Used for modern barcodes.

Invalid ISBN Invalid

0-306-40615-3

Input: The last digit changed from '2' to '3'.

Result: Checksum fails. The tool detects the typo.

Frequently Asked Questions

What is the difference between ISBN-10 and ISBN-13?

ISBN-10 is a 10-digit code used historically, while ISBN-13 is the current standard introduced in 2007 to match the EAN barcode system. ISBN-13 prefixes the old 10-digit number with "978" or "979".

Does this tool support ISBNs with hyphens?

Yes. You can paste the ISBN with or without hyphens and spaces. Our validator automatically strips non-numeric characters (except 'X') to perform the calculation.

What does the 'X' at the end of an ISBN mean?

In an ISBN-10, the last digit is a checksum. If the calculated checksum is 10, it is represented by the Roman numeral 'X' to keep the code length at 10 characters.