Validate ISBN

Validate ISBN-10 or ISBN-13 check digits and return normalized book identifiers.

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ToolISBN Validator
Input
Output
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Preview

How it works

Hyphens and spaces are removed; ISBN-10 weights digits 10 through 2 and permits X as the final value ten, while ISBN-13 alternates weights 1 and 3 across the first twelve digits. The calculated check digit must match the last character.

  • Both lengths remain supported for older and current books.
  • Separators are ignored but normalized digits are returned.

Worked example

Valid ISBN-13
Validate an ISBN-13 number (e.g., for a published book)
Input
											978-0-13-468599-1
Output
												Valid ISBN-13: 9780134685991

When to use this

Library catalogues, bookseller imports, and publishing workflows validate ISBNs.

Edge cases

  • ISBN-10 allows X only in its final position.
  • ISBN-13 uses alternating weights rather than the ISBN-10 sum.
  • Correct length alone does not guarantee a valid check digit.

References