ISBN 10 and 13: Both formats explained - these are the differences

The ISBN number helps with book searches and follows a clear pattern. However, there are two formats and our guide explains what's behind it and how the system works.

The ISBN-13 is the new standard that has replaced the old ISBN-10.

The ISBN can usually be found out very quickly. Often you can even find two ISBN numbers, namely ISBN-10 and ISBN-13.

ISBN 10 and 13: This is how the system looks

The numbers 10 and 13 stand for the number of digits in the ISBN number. There is a simple reason for the existence of these two formats:

• ISBN-10 is the original format, as it has existed for decades.
• On January 1, 2007, ISBN-13 was introduced because ten digits were no longer sufficient due to the massive and growing number of books. The combination possibilities with ten digits are very large, but it was nevertheless foreseeable that one day they will no longer be enough.
• All books published from 2007 are mandatory with the ISBN-13.
• Books that were published before have both formats. In this case, the old ISBN-10 was simply preceded by a three-digit prefix (978 or 979), so that the original number remained mostly contained. It is important to note that the last digit of the ISBN-10 is changed during this conversion, namely into a check digit, which results per special calculation from the preceding numbers.
• This structure also applies to newer books, which are provided directly with the ISBN-13. In total, the ISBN-13 consists of five groups of numbers, starting with the three-digit prefix, the one-digit country number, the five-digit publisher number and the three-digit title number, and ending with the final check digit.

An illustrative example is this classic from 1990, which has both ISBN formats in the product information. When searching for books by ISBN, both variants are basically always purposeful, there are no exceptions.