ISBN Validator (10 & 13)

About this tool

Check whether a book ISBN is valid. Supports both ISBN-10 and ISBN-13 using their respective checksum formulas.

Example

Input: 978-3-16-148410-0

Output: Valid ISBN-13

Privacy

This tool runs entirely in your browser. Your data is processed locally and never uploaded to a server.

How to use this tool

1. Paste an ISBN into the input box.
2. Choose ISBN-10 or ISBN-13 if the tool asks for a format, or let it detect the length.
3. Click Validate to check the checksum.
4. Read the result to see whether the ISBN is valid or invalid.

Step by step, what happens

1. The tool first removes common separators like spaces and hyphens so the ISBN can be checked in a clean form.
2. It then checks whether the input matches ISBN-10 or ISBN-13 rules based on length and allowed characters.
3. Next it calculates the official checksum for that ISBN type and compares it with the final check digit.
4. Finally, it shows a clear valid or invalid result, and may include a worked example or explanation of the check.

Worked example

Here is a simple ISBN-10 example you might want to verify before adding a book to a catalog.

Input: 0306406152

1. The tool reads the 10-digit ISBN and recognizes it as ISBN-10.
2. It checks the final digit against the checksum rules for ISBN-10.
3. Because the check digit matches the calculated value, the ISBN is accepted as valid.

Tips and common mistakes

• Do not include extra text like book titles or labels with the ISBN.
• Hyphens and spaces are usually fine, but the core digits must still be correct.
• An ISBN-10 can end with X, which represents a valid check digit, but only in the final position.
• If the tool says invalid, double-check for a missing digit, a typo, or the wrong ISBN type.

Frequently asked questions