day 17: what is an ISBN?

Miss a day? Visit the main post for links to each day.

One of my goals in writing this series is to help eliminate some of the surprises that can make self-publishing feel overwhelming. An ISBN is often one of those unexpected little details that pops up during the self-publishing process, and you will need to determine if it is necessary for your book.

So what exactly is an ISBN?

ISBN stands for International Standard Book Number. An ISBN is, simply put, a unique identifying number for your book. It identifies who registered the book, the title, the edition, and the format. It is a 13-digit (or 10-digit prior to 2006) number found on the copyright page of the book.

Does my book need an ISBN?

If your book is in print, then the answer is a simple yes.

For e-books, an ISBN is not always mandatory. Amazon and Barnes & Noble assign their own catalog number for e-books sold in their online stores, therefore an ISBN is not a requirement. You can still purchase an ISBN for your e-books sold there if you would like. The iBookstore does require an ISBN. If you are selling your book as a PDF, it is your choice as to whether or not you use an ISBN.

 Can I use the same ISBN for all formats?

No! If you are going to use an ISBN in your book, it must be an ISBN obtained for that specific format. For example, if you are releasing your book in print, PDF, Kindle, and ePub formats (and you have decided that you want every format to use an ISBN), you will need to obtain four ISBNs.

Where do I get an ISBN?

Just a quick note to those who may be doing a print-on-demand book through CreateSpace. At CreateSpace you have the option of having them assign a free ISBN to your book. There may be others who offer this feature, so I recommend that you check to see if this is a possibility in your particular situation.

If you need to purchase ISBNs, Bowker is the official agency for ISBNs in the United States. If you reside in another country, you will need to find out where to purchase ISBNs for that nation. The International ISBN Agency website offers more helpful information as well as a list of national agencies.