Free ISBN Validator

Validate ISBN-10 and ISBN-13 numbers instantly with our free online validator. Check digit calculation and format verification ensure your ISBNs meet international standards for book publishing and distribution.

Perfect for authors, publishers, booksellers, and librarians. Supports single ISBN validation and bulk validation for up to 50 ISBNs at once.

Validate Your ISBN

Enter your ISBN-10 or ISBN-13 number below. The tool accepts numbers with or without hyphens and instantly verifies the check digit.

Enter up to 50 ISBNs (one per line) to validate them in bulk. Results will show each ISBN's type and validation status.

Note: This tool validates the mathematical correctness of the ISBN format and check digit. It does not verify registration in the ISBN Agency database.

Professional ISBN validator for book publishing

Why Use Our ISBN Validator?

100% Free

No registration or payment required

Instant Validation

Get results immediately with accurate check digit verification

Bulk Validation

Validate up to 50 ISBNs simultaneously

Both Formats

Supports ISBN-10 and ISBN-13 validation

Frequently Asked Questions About ISBN Validation

What is an ISBN?

An ISBN (International Standard Book Number) is a unique numeric commercial book identifier based upon the 9-digit Standard Book Number (SBN). ISBNs are used by publishers, booksellers, libraries, internet retailers, and other supply chain participants for ordering, listing, sales records, and stock control purposes. The ISBN identifies the registrant as well as the specific title, edition, and format.

Why is ISBN Validation Important?

ISBN validation ensures that the ISBN you are using is correct and follows the standard format. This is crucial for accurate identification, sales and distribution, and metadata accuracy. A valid ISBN ensures that your book is correctly identified in databases and catalogs, and retailers and distributors rely on valid ISBNs to process orders and manage inventory.

How Does the ISBN Validator Work?

Our ISBN Validator checks the validity of ISBN-10 and ISBN-13 numbers by verifying their check digits. For ISBN-10, each of the first nine digits is multiplied by a weight (10 down to 2), and the sum must be divisible by 11. The check digit can be 0–9 or 'X' (representing 10). For ISBN-13, each digit is multiplied by alternating weights of 1 and 3, and the sum must be divisible by 10, with the check digit ranging from 0–9.

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

ISBN-10 is the older 10-digit format that was used until 2007, while ISBN-13 is the current 13-digit format that has been standard since 2007. ISBN-13 provides more numbering capacity and is compatible with the EAN-13 barcode system used in retail. All new ISBNs are issued in the ISBN-13 format.

Can I validate multiple ISBNs at once?

Yes, our ISBN Validator tool supports bulk validation. You can enter up to 50 ISBNs at once (one per line) and validate them all simultaneously. The results will show each ISBN's type and validation status in an easy-to-read table format.

Does the validator check if an ISBN is registered?

No, this tool only validates the mathematical correctness of the ISBN format and check digit. It does not verify whether the ISBN is registered in the official ISBN Agency database. For registration verification, you would need to check with the ISBN Agency directly.

What does the check digit in an ISBN mean?

The check digit is the last digit in an ISBN that is calculated using a specific algorithm based on the preceding digits. It serves as a validation mechanism to detect errors in the ISBN. For ISBN-10, the check digit can be 0-9 or X (representing 10). For ISBN-13, it can only be 0-9.

Can I use hyphens in my ISBN when validating?

Yes, our ISBN Validator accepts ISBNs with or without hyphens. The tool automatically removes hyphens and other non-numeric characters (except X for ISBN-10) before performing the validation, so you can enter your ISBN in any format.