Older books use a 10-digit ISBN, newer ones use 13 digits, and cataloging systems often need both. This tool validates either format and converts between them instantly.
What Is the ISBN Converter?
The ISBN Converter validates ISBN-10 and ISBN-13 check digits and converts between the two formats — ISBN-10 to ISBN-13 by adding the “978” Bookland prefix and recomputing the checksum, or ISBN-13 back to ISBN-10 when the “978” prefix is present.
How to Use It
- Open the tool at /tools/isbn-converter.
- Type or paste an ISBN — hyphens and spaces are stripped automatically.
- See both the ISBN-10 and ISBN-13 forms, each with its own check-digit validity.
- Try an example button to see the conversion in both directions.
Key Features
- ISBN-10 checksum: weighted sum mod 11, with “X” representing a check digit of 10.
- ISBN-13 checksum: the same EAN-13 barcode algorithm used at retail checkouts.
- Bidirectional conversion, with a clear note when an ISBN-13 (like a “979” prefix) has no ISBN-10 equivalent.
- Illustrative hyphenated formatting for readability.
When to Use This Tool
- Cataloging or migrating book data that mixes ISBN-10 and ISBN-13 records.
- Validating user-submitted ISBNs in a form.
- Learning how ISBN check digits work.
Try It Now
Open ISBN Converter directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Text Tools collection on WebdevToolbox — free, browser-based developer tools with no login required.