ISBN Validator and Converter

Validate ISBN-10 and ISBN-13 numbers and convert between them — free ISBN checker.

About

About the ISBN Validator and Converter

Checks whether an ISBN passes its official checksum, and converts between the ISBN-10 and ISBN-13 formats.

Booksellers and librarians use it to confirm a scanned or typed ISBN is valid before adding it to a catalog, while developers building a book-related app use it to test their own ISBN validation logic against a known-good implementation. It's one of many free data tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.

Choose what to view about this tool

Guide

Using the ISBN Validator and Converter

  1. 1

    Step 1

    Paste or type the ISBN, with or without dashes and spaces.

  2. 2

    Step 2

    Click "Check and convert".

  3. 3

    Step 3

    Read whether the checksum is valid, and see the equivalent ISBN-10 or ISBN-13, if convertible.

  4. 4

    Step 4

    Click "Clear" to check another ISBN.

  • Validates both ISBN-10 (with the X check digit) and ISBN-13 checksums
  • Converts a valid ISBN-10 to its ISBN-13 equivalent
  • Converts a valid ISBN-13 back to ISBN-10, when its prefix is 978
  • Ignores spaces and dashes automatically, so you can paste an ISBN exactly as printed
  • Clear message when the input is the wrong length or fails its checksum
  • Works entirely in your browser — nothing you enter is sent to a server
  • Free to use, with no sign-up and no limit on how many times you run it

Booksellers

Booksellers use the ISBN Validator for confirming a scanned or typed ISBN is valid before adding a title to their catalog or inventory system.

Librarians

Librarians use the ISBN Validator for checking an ISBN printed in a record against its checksum, and for converting older ISBN-10 records to ISBN-13.

Developers

Developers building a book-related app use the ISBN Validator for testing their own ISBN validation logic against a known-good implementation.

Students and researchers

Students and researchers use the ISBN Validator for confirming a citation's ISBN is correctly formed before submitting a bibliography.

Examples

ISBN Validator and Converter examples

3 worked examples

01

A valid ISBN-10 converted

0-306-40615-2 passes its checksum and converts to the ISBN-13 equivalent 978-0-306-40615-7.

02

A checksum failure

0-306-40615-3 fails validation, since changing the last digit from 2 to 3 breaks the official ISBN-10 checksum.

03

A 979-prefixed ISBN-13

9791234567896 is a valid ISBN-13, but because it starts with 979 instead of 978 it has no ISBN-10 equivalent, and the tool reports that it can't be converted.

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FAQ

Frequently asked questions

Quick answers to common questions about the ISBN Validator and Converter.

What does the ISBN Validator and Converter do?

It checks whether an ISBN-10 or ISBN-13 passes its official checksum, and converts a valid ISBN between the two formats.

Is the ISBN Validator free to use?

Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.

Is my input safe when I use this tool?

Yes. Validation and conversion happen entirely on your own device — nothing you enter is sent to a server.

Does it matter if my ISBN has dashes or spaces?

No. The tool strips spaces and dashes automatically, so you can paste an ISBN exactly as printed on a book.

What does the X mean at the end of some ISBN-10s?

In ISBN-10, X represents the value 10 as a single check digit, since a two-character "10" wouldn't fit in the fixed 10-digit format. The tool accepts X in that position.

Can every ISBN-13 be converted back to ISBN-10?

No. Only ISBN-13s that start with the 978 prefix can be converted to ISBN-10; newer 979-prefixed ISBN-13s have no ISBN-10 equivalent, and the tool tells you so.

Does a valid checksum mean the book definitely exists?

No. It only confirms the number is correctly formed according to the ISBN checksum rules, not that it's assigned to a real, published book.

Can I use this tool on my phone?

Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.

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