ISBN-13 generator — test book numbers and check digit finder

How to use the ISBN-13 generator

1. Choose the Mode: Generate test values or Validate or complete.
2. To generate, pick the Prefix: 978 (Bookland) or 979 (groups 8, 10, 11, 12). Set How many and press Generate.
3. To check, type into ISBN-13 (or the first 12 digits to get the check digit). Hyphens and spaces are fine.
4. Twelve digits give the Check digit and the Full ISBN-13. Thirteen digits give the Result with the check digit given and expected.

What it does and when to use it

Since 2007, every new ISBN has 13 digits. Library systems, bookshop software, reading-list apps and citation managers all validate it. If you build or test such software, you need numbers that pass the check but do not point at real books; if you work with books, you sometimes need to recover a check digit lost in a smudged scan.

Generated numbers are test values. For a real book, apply to your national ISBN agency. To convert an old 10-digit ISBN, or to test one, use the ISBN-10 generator. The barcode on the back cover is an EAN-13 of the ISBN, which you can draw by pasting the number into the barcode generator as EAN-13. Other retail codes are covered by the EAN-13 generator.

How it works

ISBN-13 uses the GS1 mod-10 check, just like a supermarket barcode:

1. Multiply the 1st, 3rd, 5th … 11th digits by 1 and the 2nd, 4th … 12th by 3.
2. Add the products.
3. The check digit is the gap to the next multiple of 10.

A 13-digit number counts as a valid ISBN only if it starts with 978 or 979 and the check digit is right. Test numbers are the prefix, then random digits from crypto.getRandomValues, then the check digit. With 979 the tool first picks one of the groups 8, 10, 11 or 12.

Worked examples

• A classic example ISBN. For 978030640615: 9 + 7×3 + 8 + 0×3 + 3 + 0×3 + 6 + 4×3 + 0 + 6×3 + 1 + 5×3 = 93. Seven more makes 100, so the tool shows Check digit: 7 and Full ISBN-13: 9780306406157.
• Validating with hyphens. 978-0-306-40615-7 gives Result: Valid.
• A magazine number. 9771234567003 gives Result: Invalid although the given and expected check digits are both 3, and a Reason line says An ISBN-13 must start with 978 or 979; 977 is not a book prefix.
• Test numbers. One 979 run gave 9791014754188 (group 10) and 9798786872737 (group 8).

Limits and tips

• Random digits do not follow publisher ranges, so a test ISBN may not split into valid parts.
• The tool cannot look up a title, author or publisher.
• Keep ISBNs as text so spreadsheet software does not round them.