What an ISBN Does, and Doesn't Do, for Indie Authors

New authors often treat the ISBN like a license to publish. It is not. An ISBN is a product identifier, a little like a barcode for a specific edition of a book. Knowing what it does, and what it does not do, saves money and confusion when you are getting a book into the world.

What an ISBN is

ISBN stands for International Standard Book Number. Since 2007, ISBNs have been 13 digits long. Each number identifies one specific edition and format of a book from one publisher. Booksellers, libraries, distributors and databases use it to make sure everyone is talking about the same product.

ISBNs are issued by national agencies. In the United States, the agency is Bowker, which sells ISBNs through its Myidentifiers website. Other countries have their own agencies, and in some, such as Canada, ISBNs are available to local publishers at no cost.

What an ISBN does not do

It does not give you copyright. In the United States, copyright exists automatically once an original work is fixed in a tangible form. Registering with the U.S. Copyright Office provides additional legal benefits, but that is a separate process from getting an ISBN.

It does not make a book "official." A book with no ISBN can still be a real book. Many ebooks are sold without one.

It does not guarantee distribution. Having an ISBN lets bookstores and libraries identify and order your book, but it does not get the book into their catalogs on its own. That depends on your distributor and their channels.

One ISBN per format

Every format of a book usually needs its own ISBN. A paperback, a hardcover and an ebook are three different products. A large-print edition is another. A revised edition with substantial changes typically needs a new number, while small corrections like fixing typos generally do not.

This matters for budgeting. An author planning paperback, hardcover and ebook versions may need three ISBNs for one title.

Free ISBNs from platforms

Some self-publishing platforms offer free ISBNs.

Amazon KDP offers a free ISBN for paperbacks and hardcovers published through it. Kindle ebooks do not require an ISBN at all. Amazon assigns its own identifier, the ASIN, to each Kindle book.

Other platforms, such as IngramSpark and Draft2Digital, have their own policies. Some offer free ISBNs in certain countries or for certain formats. Check the current terms before you publish, because they change.

The trade-off with a free ISBN is the publisher listing. A free platform ISBN often lists the platform, or a generic imprint, as the publisher in book databases. Some free ISBNs can only be used with that platform. If you later move that edition to a different printer or distributor, you may need a new ISBN anyway.

Buying your own

Buying your own ISBNs lets you list your own imprint as the publisher and use the same number across different distributors for that edition. Bowker sells single ISBNs and blocks of ten, one hundred and more, and the per-number cost drops considerably with larger blocks. Check Bowker's current price list, since prices change over time.

Many authors who plan to publish multiple books, or several formats of one book, find that a block of ten makes sense. It covers a few titles across formats, and it keeps the imprint name consistent.

If you buy your own ISBNs, you are responsible for entering the book's metadata, such as title, author, format and price, in the agency's database. Keep this accurate, because many retailers and libraries rely on it.

What about barcodes?

The barcode on a printed book's back cover encodes the ISBN, often along with the price. Many print-on-demand platforms generate the barcode automatically when you upload your cover or enter your ISBN. If yours does not, barcode generators are available, including through Bowker.

A simple decision guide

• Ebook only, sold mainly through Amazon: an ISBN is optional. The ASIN is enough for Kindle.
• Paperback through one platform, no plans to move: a free platform ISBN is usually fine.
• Several formats, several distributors or your own imprint name: buying your own ISBNs is often worth it.
• Selling to libraries and bookstores: an ISBN is effectively required for print editions, and a consistent publisher name helps with professional presentation.

The bottom line

An ISBN is a practical tool for identifying a specific edition of a book. It does not protect your work, prove your book is real or get it into stores by itself. For many indie authors, the right choice depends on how many formats they plan, where they want to sell and whether their imprint name matters to them. Make the decision once, write it down and apply it consistently across your catalog.