ISBN Converter

Convert an ISBN-10 to ISBN-13, or an ISBN-13 that starts with 978 back to ISBN-10. Free, no signup needed.

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Frequently Asked Questions

ISBN-10 is the older 10-digit format used before 2007. ISBN-13 is the current 13-digit standard that all new books must use. ISBN-13 starts with 978 or 979.

Most modern publishing platforms, databases, and distribution systems require ISBN-13 format. Converting ensures your book works with current systems.

Yes, the conversion follows the official ISBN standard. We add the 978 prefix and recalculate the check digit to create a valid ISBN-13.

Currently, our tool converts one ISBN at a time. Enter each ISBN-10 or ISBN-13 individually for conversion.

Yes, but only for ISBN-13s that start with 978. ISBN-13s starting with 979 cannot be converted to ISBN-10 format as they have no ISBN-10 equivalent.

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How ISBN-10 to ISBN-13 Conversion Works

An ISBN-10 and its ISBN-13 share the same nine core digits. Only the prefix and the check digit change.

1
Drop the last digit of the ISBN-10 (its check digit)
2
Put 978 in front of the remaining 9 digits
3
Recalculate the check digit: multiply the 12 digits by 1 and 3 in turn, add them up, and pick the digit that makes the total a multiple of 10

Example: 0-87654-321-2 becomes 978-0-87654-321-4.

Converting ISBN-13 Back to ISBN-10

Only ISBN-13s that start with 978 have an ISBN-10. ISBNs that start with 979, including the 979-8 ISBNs now issued in the US, have none, and the ISBN-13 is the one to use.

1
Check that the ISBN-13 starts with 978
2
Drop the 978 and the last digit, leaving 9 digits
3
Recalculate the check digit: multiply the 9 digits by 10 down to 2, add them up, and pick the digit that makes the total divisible by 11 (10 is written as X)

Example: 978-0-87654-321-4 becomes 0-87654-321-2.

ISBN-10 Format (1970-2007)

The original ISBN system was created to uniquely identify books and streamline inventory management in the publishing industry. All books published before 2007 received ISBN-10 numbers, and many of these remain in circulation today.

0-87654-321-2

10 digits with possible 'X' as check digit

ISBN-13 Format (2007-Present)

ISBN-13 was introduced to align with the global EAN-13 barcode standard and provide more numbering capacity for the growing publishing industry. Since January 2007, all new ISBN registrations use the 13-digit format, making it the current standard for book identification worldwide.

978-0-87654-321-4

13 digits starting with 978 or 979 prefix