ISBN-10 generator — test numbers and the mod-11 check digit, X included

How to use the ISBN-10 generator

1. Choose the Mode: Generate test values or Validate or complete.
2. To generate, leave the Prefix on Any group, set How many and press Generate.
3. To check, type into ISBN-10 (or the first 9 digits to get the check digit). Hyphens and spaces are ignored, and a lower-case x is accepted.
4. Nine digits give the Check digit and the Full ISBN-10. Ten characters give Result, Check digit given and Check digit expected.

What it does and when to use it

ISBN-10 was the book number standard until the end of 2006. It still appears on millions of older books, in library catalogues and in second-hand book data, so cataloguing tools and book-trade software must validate it. The X check character is a classic source of bugs, because a field that accepts digits only will reject roughly one valid ISBN in eleven.

Use this page to make test data that includes X endings, to check numbers typed from old books, or to recover a check character from the first nine digits. For current 13-digit ISBNs and the 978/979 prefixes, use the ISBN-13 generator. For numbers in other systems that use an 11-based check, such as VINs, see the VIN generator. Shop barcodes use a different, 10-based rule; see the EAN-13 generator.

How it works

1. Multiply the nine digits by 10, 9, 8, 7, 6, 5, 4, 3 and 2, in that order.
2. Add the products and find the remainder after dividing by 11.
3. The check value is 11 minus that remainder, with 11 becoming 0 and 10 becoming X.

A complete ISBN-10 is valid when the tenth character matches. Test numbers are nine random digits from crypto.getRandomValues followed by their check character.

Worked examples

• A standard example. For 030640615: 0×10 + 3×9 + 0×8 + 6×7 + 4×6 + 0×5 + 6×4 + 1×3 + 5×2 = 130. 130 ÷ 11 leaves 9, and 11 − 9 = 2, so 0-306-40615-2 gives Result: Valid.
• An X ending. For 080442957 the sum is 199, which leaves 1; 11 − 1 = 10, so the tool shows Check digit: X and Full ISBN-10: 080442957X.
• A wrong last digit. 0-306-40615-3 is invalid, with Check digit expected: 2.
• A letter in the middle. 03064A615 is refused with “Use digits only.”

Limits and tips

• Only the last character may be X. An X anywhere else makes the number invalid.
• The check catches any single wrong digit and any swap of two neighbouring digits.
• The tool does not look up titles or convert to ISBN-13 for you.