KDP ISBN rules: free KDP ISBN vs your own, and ebooks

Ebooks

KDP does not require an ISBN for a Kindle ebook, and the free KDP ISBN is only offered for print. Ebooks have an optional Publisher field where you can enter your own name or publishing company. It cannot reference Amazon, Kindle, KDP, another publisher or a website.

Free KDP ISBN

For paperbacks and hardcovers you can choose Get free KDP ISBN in the content step. KDP registers it with Bowker, the US ISBN agency, using your book details. The imprint shows as “Independently published” on the detail page, and the ISBN cannot be used outside KDP.

Your own ISBN

An ISBN bought from Bowker or your national agency can be used on KDP and on other publishing services. The imprint is the publisher name you registered, such as a business or brand name. KDP checks the title, author and imprint against the agency’s record and blocks publishing on any mismatch. The Imprint field holds up to 100 characters.

Changing an ISBN

An ISBN can be changed only while the book is still a draft. Once published, changing the ISBN, title or author means unpublishing and creating a new edition.

Worked example

You plan a paperback on KDP and a hardcover through another printer. With a free KDP ISBN on the paperback, only KDP can sell that edition. Buy two ISBNs instead, one per format, register both under the same imprint, and you can sell either edition anywhere while showing your imprint.

Common mistakes

• Typing “n/a” or “unknown” as the imprint.
• Reusing one ISBN across formats or for a substantially changed edition.
• Expecting to switch from a free ISBN to your own after publishing.

Amazon changes these rules; the linked KDP help pages are the authority.