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ISBN Numbers For Books

Learn what an ISBN is, why you need it, and how to get one.

What is an ISBN?

What is an ISBN?

Every book on the market possesses its own unique ISBN (International Standard Book Number), a numeric identifier used around the world to identify books. If you plan to sell your book in a bookstore, through an online retailer, or to your local library, you’ll need to have a 13-digit ISBN number assigned to it. The process of getting an ISBN is not complicated, but there are important details you need to be aware of as you navigate the process.

One Book, Multiple ISBNs

In order to ensure that you are making your book accessible to all of your potential readers, you may want to provide different format choices for your book. Multiple book formats and editions will each require a unique ISBN. For example, a softcover edition requires a different ISBN than a hardcover edition. Or if you decide to have a printed book format, eBook format, and an audiobook, each format will need its own ISBN.

Buying an ISBN

ISBNs are issued to publishers, who then assign them to individual books. Because a self-published author is considered a publisher, you can purchase an ISBN for your own book. BookBaby makes buying an ISBN easy and affordable. One of the many benefits of self-publishing your book with BookBaby, is the ability to buy a single ISBN at the rate of $49 (each) while you’re in the process of making your book.

You also can purchase an ISBN directly from Bowker at Keep in mind that a single ISBN from Bowker costs $125, and 10 ISBNs cost $250. There’s no difference between an ISBN purchased from BookBaby vs one from Bowker. BookBaby purchases blocks of ISBNs from Bowker to provide to our authors.

Where does a book ISBN go?

An ISBN goes on the copyright page and should be included in the Cataloging in Publication (aka CIP data) block, if you use one. ISBN numbers are also usually printed on the back covers of books as part of the bar code when the book is being sold.

What is an Amazon ASIN?

BookBaby offers book distribution to the most stores worldwide, including Amazon, one of the most impactful platforms to sell your book. An ISBN is not necessary for publishing your Kindle eBook on Amazon. Instead, Amazon assigns its own identifier, the ASIN (Amazon Standard Identification Number), for all Kindle eBooks. However, your print version will still be identified by its ISBN. Amazon will only be assigning an ASIN for your Kindle eBook version.

ISBNs for Authors Outside of the USA

If you don’t reside in the United States, you still can purchase an ISBN directly from BookBaby or from one of over 160 ISBN agencies worldwide. Each agency is responsible for assigning ISBNs to publishers residing in their respective geographic territory.

Tip: If you print your book in another language, you’ll need a new ISBN.

Revisions and ISBNs

After your book goes through the editing process, it may need minor revisions. As long as it doesn’t have any substantial changes and isn’t considered a reprint or a new edition, you won’t need a new ISBN.

Be mindful that this is subjective. ISBN guidelines state that a major revision, or the addition of completely new material, would be defined as a substantial change. The process is the same if there are substantial elements deleted from your book.

After purchasing an ISBN, your book is ready to sell, but this doesn’t mean it is automatically copyrighted. Get the breakdown on how to copyright your book here.

Need to purchase an ISBN for your book?

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