ISBN Validator

An ISBN (International Standard Book Number) is a unique numeric identifier assigned to each edition of a book. There are two formats in use:

ISBN-13 (Current Standard)

A 13-digit number with the structure: prefix-group-publisher-title-check

• Prefix: 978 or 979 (EAN/Bookland)
• Registration Group: Identifies the country or language area
• Registrant: Identifies the publisher
• Publication: Identifies the specific edition
• Check Digit: Single digit for error detection

ISBN-13 Check Digit Algorithm:

1. Multiply each of the first 12 digits alternately by 1 and 3
2. Sum all the products
3. Check digit = (10 − (sum mod 10)) mod 10

ISBN-10 (Legacy Format)

A 10-digit number (last digit can be 'X' representing 10).

ISBN-10 Check Digit Algorithm:

1. Multiply each of the first 9 digits by its position (10, 9, 8, ... 2)
2. Sum all the products
3. Check digit = (11 − (sum mod 11)) mod 11 (if 10, use 'X')

ISBN-10 to ISBN-13 Conversion

Any ISBN-10 can be converted to ISBN-13 by prepending "978" and recalculating the check digit using the ISBN-13 algorithm.

Limitations

This validator checks:

• Format and length correctness
• Check digit validity
• ISBN-10 to ISBN-13 conversion

It does NOT verify:

• Whether the book actually exists
• Publisher or title information

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.