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About the ISBN Standard

"ISBN" stands for "International Standard Book Number". An ISBN is a number, not a bar code. One agency per country is designated to assign ISBNs for the publishers and self-publishers located in that country. The U.S. ISBN Agency cannot assign ISBNs to publishers and self-publishers located outside the United States and its territories.

The ISBN identifies the title or other book-like product (such as an audiobook) to which it is assigned, but also the publisher to be contacted for ordering purposes. If an ISBN is obtained from a company other than the official ISBN Agency, that ISBN will not identify the publisher of the title accurately. This can have implications for doing business in the publishing industry supply chain.

ISBNs are assigned to publishers and self-publishers as follows: 1, 10, 100, 1,000, 10,000 or 100,000 numbers.

When participating in the ISBN standard, publishers and self-publishers are required to report all information about titles to which they have assigned ISBNs. For more than thirty years, ISBNs were 10 digits long. On January 1, 2007 the ISBN system switched to a 13-digit format. Now all ISBNs are 13-digits long. If you were assigned 10-digit ISBNs, you can convert them to the 13-digit format at the converter found at this website. A 10-digit ISBN cannot be converted to 13-digits merely by placing three digits in front of the 10-digit number. There is an algorithm that frequently results in a change of the last digit of the ISBN.

Important Notice: Changes to ISBN Prefixes

The United States ISBN Agency will soon begin assigning ISBNs starting with the prefix element 979 (in addition to the ISBNs with prefix element 978 we currently assign). This is necessary because the inventory of certain ISBN block sizes starting with 978, such as 10,000, 100,000 and 1,000,000, are dwindling.

What does this mean for publishers, libraries and retailers?
Prior to 2007, the ISBN was 10 digits in length. In January 2007, the 13-digit ISBN launched to increase the capacity of the ISBN system. To date, 13-digit ISBNs assigned by the U.S. ISBN Agency include the 978 prefix, which allowed systems to contain both 10- and 13-digit ISBNs for all books. However, a 13-digit ISBN starting with 979 does not have an equivalent 10-digit ISBN. Once this change takes place, only 13-digit ISBNs starting with 978 or 979 should be used to identify a book.

Changes to country classifications
Currently, the U.S. ISBN Agency assigns ISBNs starting with either 978-0 or 978-1. The 0 and 1 indicate assignment by an ISBN Agency in an English-speaking region. The 979 assignments will start with 979-8. The 8 will be unique to the United States. Of course, as with the 978-0 and 978-1, an ISBN starting with 979-8 will allow U.S. publishers and self-publishers to market their books anywhere in the world.

Questions? Bowker is happy to help. Please contact us at isbn-san@bowker.com.