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ISBN Validator - Validate ISBN-10 and ISBN-13

ISBN Validator

Validate ISBN-10 and ISBN-13 book identification numbers

Enter an ISBN-10 or ISBN-13 number (with or without hyphens)

About ISBN Numbers

ISBN (International Standard Book Number) is a unique numeric commercial book identifier. Publishers purchase ISBNs from an affiliate of the International ISBN Agency. An ISBN is assigned to each separate edition and variation of a publication. For example, an e-book, audiobook, and paperback edition of the same book would each have a different ISBN.

ISBN Format

There are two versions of ISBN in use today:

  • ISBN-10: 10 digits, used from 1970 to 2006
  • ISBN-13: 13 digits, standard since 2007 (required since 2007)

ISBN-10 Structure

An ISBN-10 consists of four parts:

  1. Group identifier: Country, language, or geographic area (1-5 digits)
  2. Publisher code: Identifies the publisher (varies in length)
  3. Title number: Identifies the specific title (varies in length)
  4. Check digit: Single digit for error detection (can be 0-9 or X for 10)

Example: 0-306-40615-2

ISBN-13 Structure

ISBN-13 uses the EAN-13 barcode standard and consists of:

  1. Prefix: Either 978 or 979 (EAN.UCC prefix)
  2. Group identifier: Country, language, or geographic area
  3. Publisher code: Identifies the publisher
  4. Title number: Identifies the specific title
  5. Check digit: Single digit for error detection

Example: 978-0-306-40615-7

ISBN-10 Validation Algorithm

ISBN-10 uses a weighted checksum calculation:

  1. Multiply each of the first 9 digits by its position (10, 9, 8, ..., 2)
  2. Sum all the results
  3. Calculate the remainder when divided by 11
  4. If remainder is 0, the check digit is 0; otherwise, check digit is 11 minus the remainder
  5. If check digit is 10, it's represented as 'X'

ISBN-13 Validation Algorithm

ISBN-13 uses a simpler alternating weight checksum:

  1. Multiply each of the first 12 digits alternately by 1 and 3
  2. Sum all the results
  3. Calculate (10 - (sum modulo 10)) modulo 10
  4. This result should equal the check digit

Example Validation: ISBN-13

Let's validate ISBN-13: 978-0-306-40615-7

Step 1: Remove hyphens: 9780306406157
Step 2: Multiply first 12 digits by alternating 1 and 3:
        (9×1) + (7×3) + (8×1) + (0×3) + (3×1) + (0×3) +
        (6×1) + (4×3) + (0×1) + (6×3) + (1×1) + (5×3)
        = 9 + 21 + 8 + 0 + 3 + 0 + 6 + 12 + 0 + 18 + 1 + 15
        = 93
Step 3: Calculate check digit: (10 - (93 % 10)) % 10 = 7
Step 4: Compare with last digit: 7 = 7 (Valid!)

Converting ISBN-10 to ISBN-13

To convert an ISBN-10 to ISBN-13:

  1. Remove the ISBN-10 check digit
  2. Prefix the remaining 9 digits with "978"
  3. Calculate the new ISBN-13 check digit
  4. Append the check digit

Example: 0-306-40615-2 becomes 978-0-306-40615-7

When to Use ISBN Validation

  • Library Systems: Validate book entries in library catalogs
  • Bookstore Inventory: Ensure accurate book identification in POS systems
  • Publishing Platforms: Verify ISBN accuracy when registering books
  • E-commerce: Validate ISBNs in online bookstore listings
  • Citation Management: Check ISBN accuracy in bibliography software
  • Book APIs: Validate ISBN input for book information APIs

Common ISBN Formatting

ISBNs can be written in various formats:

  • With hyphens: 978-0-306-40615-7 (most common)
  • With spaces: 978 0 306 40615 7
  • Without separators: 9780306406157
  • With "ISBN" prefix: ISBN 978-0-306-40615-7
  • With "ISBN-13" prefix: ISBN-13: 978-0-306-40615-7

Test ISBN Numbers

Format Valid ISBN
ISBN-10 0-306-40615-2
ISBN-13 978-0-306-40615-7
ISBN-10 with X 0-8044-2957-X
ISBN-13 (979 prefix) 979-10-90636-07-1

ISBN Prefixes and Registration Groups

The first digits of an ISBN identify the registration group:

  • 0 or 1: English-speaking countries
  • 2: French-speaking countries
  • 3: German-speaking countries
  • 4: Japan
  • 5: Former Soviet Union countries
  • 7: China
  • 80-94: Various countries
  • 950-989: Various smaller countries

Limitations

This validator checks format and checksum only. It does NOT:

  • Verify if the ISBN is registered with the ISBN agency
  • Check if the book actually exists
  • Validate against publisher records
  • Fetch book information (title, author, etc.)

Best Practices

  • Always validate ISBNs before adding books to databases
  • Accept both ISBN-10 and ISBN-13 formats in modern systems
  • Store ISBNs without hyphens in databases for easier searching
  • Display ISBNs with hyphens for better readability
  • Consider using ISBN lookup APIs for additional book information
  • Remember that the same book can have multiple ISBNs (different editions, formats)

Additional Resources