Discover what ISBNs do and how imprint names are associated with those unique numbers.

What is an ISBN?

An ISBN is a unique 13-digit number assigned to majority of published book. It typically starts with 978 or 979, and identifies various attributes about a book (e.g. edition, publisher name, page count, etc.).

ISBNs are used by booksellers, libraries, publishers, and retailers (like Amazon) to identify the book, manage their inventory, and list it for sale. Amazon also assigns an ASIN (Amazon Standard Identification Number) to each book, which is similar to an ISBN. When you publish through KDP, you’ll notice both numbers are assigned to your book.

If you are publishing a low-content book, you can choose to either use your own ISBN or publish without an ISBN. If you publish without an ISBN, we’ll automatically assign an ASIN for your book. Learn more about low-content books.

Note: An ISBN is required for publication of paperback and hardcover books. eBooks don’t require an ISBN number to be published on KDP.

What is an Imprint?

Imprint names are another way books are identified, beyond using an ISBN. Publishers often release books under a different name than their company name, i.e. an imprint. Example: Penguin Random House is the publishing company name, but they often issue books under the imprint, Penguin Classics.

If you’ve registered your ISBN with an imprint outside of KDP, you’ll need to provide both pieces of information exactly how they’re registered, so we can validate your book. However, if you’re using KDP’s free ISBN, we’ll automatically assign your imprint as “Independently published.”

More ISBN resources

• Can I use an ISBN I already own?
• Does KDP offer free ISBNs?
• How do I troubleshoot errors with my ISBN or imprint?

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