When publishing a book with KDP, you’ll be asked to provide an ISBN and imprint (i.e. publisher). This article explains what an ISBN and imprint are, while detailing requirements for publishing.

What is an ISBN?

An ISBN (International Standard Book Number) is a unique identifier for books. It helps bookstores, libraries, distributors, and readers find and reference your book correctly. Each format of your book (paperback vs hardcover) needs its own ISBN. eBooks and low-content books are the only formats where an ISBN is optional.

The same ISBN cannot be reused across multiple book formats or new editions that introduce significant changes from the original version.

KDP allows two options for ISBNs:

1. You can use a free ISBN from KDP (paperback and hardcover books only).
2. You can purchase your own ISBN.

Note: Free ISBNs from us can only be used on KDP. They cannot be used to publish outside of KDP.

If you purchase your own ISBN, you must enter the same details (i.e. book title, author name, publisher) in KDP that you used to register the ISBN.

What is an Imprint?

An imprint is the name of the publisher associated with your book’s ISBN. If you buy your own ISBN, you can list your own publishing imprint (such as your business or brand name). If you use a free ISBN from KDP, the imprint will appear as “Independently published.”

If you use your own ISBN, KDP will check whether your book’s imprint matches what’s on file with the ISBN agency (e.g. Bowker). If there’s a mismatch, you won’t be able to publish.

Note: Entering ISBN and imprint details are case-sensitive. Even extra spaces at the end of the imprint name can cause mismatch errors. Do not enter placeholders, such as “unknown” or “n/a.”

Helpful resources

• Get and compare ISBNs
• Change or view your ISBN
• Troubleshoot ISBN errors
• Barcodes with ISBNs