Do I Need an ISBN for My Book? What Authors Should Know

Few parts of self-publishing cause as much confusion as the ISBN. Some authors buy a stack of them before they have a finished draft. Others never think about it until a bookstore asks for one. The short answer is that most print books need an ISBN, many ebooks do not, and who owns the number matters more than most people realize.

What an ISBN actually is

ISBN stands for International Standard Book Number. It is a 13-digit identifier that points to one specific edition and format of a book. Retailers, distributors and libraries use it to order, track and catalog your title. It also records who the publisher of record is.

An ISBN is not a copyright. Your copyright exists as soon as you write the work. The ISBN is simply a product identifier for the supply chain.

When you need an ISBN

• Print books sold through retailers. Paperbacks and hardcovers almost always need one.
• Books you want in bookstores or libraries. Their ordering systems rely on ISBNs.
• Ebooks on some platforms. Certain retailers and aggregators require an ISBN for ebooks, while others do not.

When you may not need one

• Kindle ebooks sold on Amazon. Amazon assigns its own identifier, the ASIN, so no ISBN is required.
• Books you only sell directly, such as copies you hand out at events or sell from your own website.
• Private editions, like a family memoir printed only for relatives.

Where to get an ISBN

Each country has an official ISBN agency, and you buy from the one where you, as the publisher, are based.

• United States: Bowker is the official ISBN agency. You buy through its website, myidentifiers.com.
• United Kingdom and Ireland: Nielsen is the official agency.
• Other countries: many have their own agency, and in some places ISBNs are free through a national library.

In the US, buying a single ISBN costs considerably more per number than buying a block of ten or more. If you expect to publish more than one format or more than one book, a block is usually the better value. Check Bowker's current prices before you buy, since they change from time to time.

The free KDP ISBN: what you gain and what you give up

Amazon KDP offers a free ISBN for paperbacks and hardcovers. For many authors it is a sensible choice, but it comes with trade-offs:

What you gain

• It costs nothing.
• Setup is quick and handled entirely inside KDP.
• It works perfectly well for books sold on Amazon.

What you give up

• KDP is listed as the publisher of record, not you or your imprint.
• You cannot use that ISBN with another printer or distributor, such as IngramSpark.
• If you later want wider distribution, you will need a new ISBN, which creates a separate edition.

If your plan is Amazon only, the free ISBN is usually fine. If you want bookstores and libraries to order your book, or you want your own imprint name on the listing, buy your own.

One ISBN per format, and sometimes per edition

This is the rule that catches most authors out. Every format needs its own ISBN:

• Paperback: one ISBN.
• Hardcover: a different ISBN.
• Ebook, if you use one: a third ISBN.
• Audiobook, if the platform requires it: another one.

A new edition with significant changes, such as substantial new content or a different trim size, also needs a new ISBN. Fixing a handful of typos does not. A new cover on its own generally does not either, though rules can vary by retailer.

Setting up your imprint

When you buy your own ISBNs, you choose a publisher name to register them under. This is your imprint. It can be your own name or a simple business name. A short, professional imprint name looks better on retail listings than a personal name, and it lets you publish future books under the same banner.

1. Choose an imprint name and check that no one else is using it for books.
2. Buy your ISBNs from Bowker under that imprint name.
3. Assign each ISBN to a specific title and format in your Bowker account.
4. Enter the matching ISBN on each platform where that format is sold.
5. Keep a simple spreadsheet so you always know which number belongs to which edition.

Common ISBN mistakes to avoid

• Reusing one ISBN across formats. Your paperback and hardcover each need their own number, or retailers will mix up the listings.
• Buying a single ISBN when you will need several. If you plan a paperback, an ebook and maybe a hardcover, a block usually costs less overall.
• Forgetting to update your ISBN record. In your Bowker account, fill in the title, format, trim size and price so retailers and libraries see accurate details.
• Changing the ISBN on an existing edition. Once a book is live, its ISBN stays with that edition. A real new edition gets a new number.

Do you need a barcode?

Print books sold in stores need a barcode on the back cover, which encodes the ISBN. KDP and most print-on-demand services add one automatically if you leave space for it. If you are printing with a traditional printer, your cover designer can create it from your ISBN.

So, do you need an ISBN? For a Kindle ebook on Amazon, no. For a paperback, yes, and the bigger question is whether to use the free KDP number or own your own. If you are unsure which suits your plans, our team can walk you through it in a free consultation.