A Guide to Book Identifiers

Okay, so you are writing a book… Congratulations! 

Now that you're preparing to publish your book, you have likely encountered terms like “ISBN” and “ASIN.” 

What are they, and do you need them? Let's break it down.

What is an ISBN?

ISBN stands for International Standard Book Number. It's a unique 13-digit identifier assigned to each edition of a book. Think of it as a product barcode for books. This number helps publishers, booksellers, libraries, and readers easily identify and track specific books.

Key Features of an ISBN: 

• Globally Recognized: Used worldwide to identify books. 
• Edition Specific: A new ISBN is required for each new edition (e.g., hardcover, paperback, large print, audio, ebook, revised edition) of the same book. 
• Identifies the Publisher: The ISBN contains a publisher prefix, revealing who published the book. 
• Used in the Supply Chain: Essential for ordering, stocking, and selling books through traditional channels. 

What is an ASIN?

ASIN stands for Amazon Standard Identification Number. It's a 9- or 10-character alphanumeric identifier assigned by Amazon to products listed on their platform. While often used for books, it's also given to other items sold on the site.

Key Features of an ASIN: 

• Amazon Specific: Only used within the Amazon ecosystem. 
• Product Specific: A unique ASIN is assigned to each product listing on Amazon. Note that Amazon also considers different editions as completely separate products, even if they are linked together on their sales page.
• Used for Amazon Sales: Essential for selling on Amazon and tracking your book there. 

What's the Difference?

The key difference is that an ISBN is an industry-wide identifier, while an ASIN is specific to Amazon.

Do I need an ISBN?

If you plan to sell a physical copy of your book through bookstores, libraries, or other retailers outside of Amazon, then yes, you need an ISBN. 

This is especially important if you plan to have your book available through IngramSpark or other distributors. 

If you are only selling your book as an ebook, especially if it is exclusively on Amazon, then you technically do not need an ISBN. Amazon will assign it an ASIN, and other retailers like Kobo will assign it a fake ISBN for sales through their stores.

Do I need an ASIN?

If you plan to sell your book on Amazon, then yes, you need an ASIN. Amazon will automatically assign one when you list your book, whether you have an ISBN or not. You don’t even need to apply for one and don’t actually have a choice if you plan to sell your book through Amazon’s retail stores.

How to Get an ISBN

There are three primary ways for you to get an ISBN for your book.

1. You can register for your own block of ISBNs through an official ISBN Agency. This is the “ideal” method, because you are the publisher of record and it gives you the most options for what you do with your book. The downside of this method is that in some countries, such as the United States, it is expensive.
2. You can publish your book through a third party. This is known as “traditional publishing” and the publishing company will supply the ISBN if they are publishing the book and you don’t need to worry about it.
3. You can accept a third-party ISBN. This is the “Free ISBN” you can get through a self-publishing platform such as KDP Print, Ingram Spark, or Draft2Digital. You will be the publisher of the book, but for that specific edition they’ll be the publisher of record and you can only print that book through whoever is providing the ISBN to you. You would have to publish a new edition if you wanted to publish with somebody else.

Another way to get an ISBN is by buying one from a reseller, but I only mention that because I would almost always advise against that. It is more of a hassle than it’s worth, and if you are going to use somebody else’s ISBN you might as well take advantage of the free ones that KDP Print and Ingram Spark give away.

It's important to have a plan for your ISBN, even if that means putting off getting one until later. If you are only planning on creating an ebook, then I would argue that you can wait to get one until later. There isn’t a huge advantage of assigning one to your ebooks unless you are specifically going for the larger awards or a newspaper bestseller list, because most of the retailers either don’t require one or don’t even use it internally if you do provide one. 

You also won’t need one right away if you are selling or giving your book away direct to consumer.

If part of your plan is to get the book available in print, however, then you’ll need to decide how you want to get your ISBN and budget accordingly. 

If you are going to sell your book wide and not just through Amazon, then it is probably worth looking into where you can register for them in your country and how long that process will take. 

In the United States, you can access your ISBNs pretty much right away after checking out on Bowker’s MyIdentifiers website, but it will cost as much as $125 per ISBN.

If you don’t have the budget for it, and don’t mind if your company shows up as the publisher of record, then it may make more sense to accept the free ISBN from KDP Print, and either plan on republishing a new edition everywhere at a later time or just create a wide-distribution-specific edition using the free ISBN from Ingram Spark or D2D.

Amazon has stopped listing similar editions with different ISBNs if they have another version already available through their own system, so new sales are less likely to be impacted by having different identifiers on your books. The disadvantage of course is that it can still play havoc with the secondary market sales of your books.