New Year, New ISBN Prefix!

Welcome to 2020, the year when the United States ISBN Agency will begin assigning ISBNs that start with a 979 prefix. Twelve years after the 13-digit ISBN was launched in order to increase the capacity of the ISBN system, the inventory of some ISBN block sizes starting with 978, such as 10,000, 100,000 and 1,000,000, is now dwindling, meaning that a new prefix is needed — 979!

What’s the big deal, you may be wondering. Well, the current 13-digit ISBNs, which use a 978 prefix, allow systems to contain both 10- and 13-digit ISBNs for all books. However, 13-digit ISBNs starting with 979 are not backward compatible — they don’t have an equivalent 10-digit ISBN — so trying to convert a 979 ISBN into a 10-digit ISBN will result in serious errors, such as ISBNs being duplicated, and potentially orders being fulfilled incorrectly. From now on, therefore, all ISBNs must be recorded in all systems and communicated to partners ONLY in their complete 13-digit form (and never in any 10-digit form). 

Please also note that these new 979 assignments will start with 979-8, where the 8 is unique to the United States — although U.S. publishers and self-publishers of books assigned this prefix will, of course, still be able to market their books anywhere in the world. 

All these changes have already been widely announced by Bowker (which operates the US ISBN Agency), including via BISG, the Library of Congress, OCLC, American Library Association, ProQuest, and Ex Libris. And Bowker will continue to assign ISBN blocks starting with 978 until its inventory of each specific block size has been exhausted, when it will be replaced with 979.  Because there is still a decent amount of inventory of 978 ISBNs in the smaller blocks (10, 100 and 1,000), this may not happen for several years. 

If you haven’t yet updated your systems and communications to reflect these changes, make it your New Year’s resolution to do so!  For more information, see Changes to United States ISBN Prefixes — or contact Bowker directly at