Monday, January 24, 2011

What is an ISBN?

It’s an International Standard Book Number. But why do books have them? And do they have to?

I’ll answer the last question first. No, your book doesn’t have to have one, but it’s a good idea.

First, more on what an ISBN is. There are now two types, 13 digit and 10 digit. The originals were 9 digits, SBNs (not International), and started out in Dublin in 1966. In 1970, the 10 digit ISBN was started, and in 2007 the 13 digit. Each print book is assigned a 13 digit ISBN today. It’s not actually required, but most places won’t sell a book without one.

What does it mean? Each part has a meaning, and I suppose there are some people who can look at them and read them. Kind of like the auto parts guy that looked at my VIN last week and told me my car is a 2002. I misremembered it as a 2001. I was very impressed he could do that!

These two numbers correspond and are for the same book:
1456348574 & 978-1-4563-4857-1 They are for my short story collection and were assigned by Createspace. The same book as an ebook has the number 978-1-4523-4514-7, assigned by Smashwords.

978 in the second number is the EAN (European Article Number, since these started in Europe). 978 means this is a book. 979 is also used for books. This number seems to be used for both print and e-books, although an e-book must have a different ISBN than its print counterpart.

1, in both numbers, is the group identifier. This is used for language and 0 or 1 are used for English. French is 2, German is 3. This number is 1-5 digits with 99936 being Bhutan. For rare languages, the group identifier is left off.

Two other parts are the same in both. Larger publishers with more titles will use a shorter publisher number so they can have larger title numbers. I don’t know how many digits are  being used for publisher and title for my book, but the numbers are 4563-4857, which leads me to believe the publisher is 4563 and the title is 4857.

The last digit is a check digit: 4 and 1 in my example. X is used to mean 10, by the way. This is used for an incredibly complicated calculation to see if the ISBN is valid.

Amazon used the same number that Createspace created for the paperback, but assigned an ASIN (Amazon Standard Identification Number) for the e-book. A Kindle e-book needs an ASIN rather than an ISBN, for some reason, and doesn’t use the Smashwords number. Of course, they don’t use the Smashwords files, either. But while Amazon paperbacks carry over the ISBN from Createspace, they don’t use those same files. The e-book ASIN is B0049B2C2A and is used only by Amazon internally.

These numbers are used as marketing tools to differentiate the products. I suppose it’s possible for two different books to have the same title and same author name, by coincidence. It’s certainly true that many books have similar, even identical titles.

The numbers have to be bought in blocks of at least 10 from the 160 of so suppliers worldwide. Self-publishing online sites have usually purchased them already and they are free when you publish with them. I believe there are places to buy individual numbers, also, but I don’t what they are.

By the way, ISSNs (International Standard Serial Numbers) are assigned to periodicals and ISMNs (International Standard Music Numbers) for sheet music.

Information from that article and Bowker bar code service at


  1. this is an awesome blog - so glad i found it :)

  2. Thank you, Melanie! Welcome to ATW. We hope you'll return, too.