Short answer. KDP ISBN vs own ISBN: the free KDP ISBN costs nothing, but it works only on KDP and your imprint shows as "Independently published." Your own ISBN costs money and can go to other printers too. Your ebook needs neither. Pick your own only if the print book will be sold outside KDP.
Key points
- A free KDP ISBN is for paperbacks and hardcovers only. KDP says ebooks do not need an ISBN.
- The free one can only be used on KDP.
- With the free one, the publisher field reads "Independently published."
- Your own ISBN must match what you registered with the agency, down to the case and spaces.
- Once the book is published, the ISBN cannot be changed without a new edition.
- Our KDP listing prep service writes your title and subtitle fields ready to paste, so you can copy them to match your ISBN record.
KDP ISBN vs own ISBN: what is the difference?
Who owns the record, and where you can use it. KDP's "Get an ISBN" page says a free ISBN is registered by KDP with Bowker, the US ISBN agency, and can be used only with KDP.
An ISBN you buy is registered to you. You can use it for the same book on other publishing services. You also choose the imprint, which is the publisher name readers see on the product page.
| Free KDP ISBN | Your own ISBN | |
|---|---|---|
| Cost | Free | You pay the agency |
| Where it works | KDP only | KDP and elsewhere |
| Publisher shown | Independently published | Your imprint name |
| Formats | Paperback, hardcover | Any |
Every row is from KDP's "Get an ISBN" page.
Do I need an ISBN for my Kindle ebook?
No. KDP's ISBN page says ebooks and low content books are the only formats where an ISBN is optional, and its "Get an ISBN" page says "You don't need an ISBN for eBooks on KDP."
Our own sample ebook shows this. The EPUB we built on 10 October 2026, a chapter of Pride and Prejudice, carries a generated ID inside the file (a long "urn:uuid" code), not an ISBN. An ebook file needs some identifier. It does not need to be an ISBN.
How many ISBNs does one book need?
One for each print format. KDP says the paperback and the hardcover each need their own ISBN, and the same ISBN cannot be reused across formats.
A new edition with significant changes also needs a new ISBN. A typo fix in the same edition does not need one, by our reading of the same page.
If you are adding a hardcover to a live paperback, our post on KDP hardcover requirements covers what else changes.
When is your own ISBN worth paying for?
When the print book will be sold through a printer other than KDP, or when you want your own imprint name on the product page.
If you will only ever print through KDP, the free one does the job. The only visible difference is "Independently published" on the product page.
The trap is choosing the free one and changing your mind later. KDP's "Change or view your ISBN" page says an ISBN cannot be changed once the book is published. You would have to unpublish and publish a new edition.
The fix we do for this: KDP listing prep writes your title, subtitle, description, 7 keywords and 3 categories as text ready to paste. It costs $99 and takes 2 business days, and we never log in to your account. Ask us about your listing.
Why does KDP reject my own ISBN?
Almost always a mismatch. KDP checks that the imprint you type matches what is on file with the ISBN agency, and if it does not, you cannot publish.
KDP warns that the check is case sensitive, and that even an extra space at the end of the imprint name can cause the error. It also asks you not to type placeholders such as "unknown" or "n/a". The imprint field takes up to 100 characters.
Copy the title, author name and imprint straight from your ISBN agency record, as KDP suggests. If you just updated that record, KDP says to wait 5 business days before using it.
Where does the barcode go?
On the back cover. KDP adds a barcode for you if you leave the space clear. Our sample wrap is a 6 x 9 inch, 384 page book, built on 10 October 2026. Its back cover keeps a plain white 2 x 1.2 inch box in the lower corner, 0.25 inch from the spine fold and the bottom trim, for that reason.
Our post on KDP paperback cover size shows the full cover layout.
What else do authors ask about KDP ISBN vs own ISBN?
Yes. KDP lists its cost as free.
No. KDP says free ISBNs cannot be used to publish outside KDP.
Only before the book is published. After that, it takes a new edition.
No. KDP says ebooks do not need one.
"Independently published."
What should you do next?
Decide where the print book will be sold. KDP only means the free ISBN is enough. Anywhere else means buying your own before you publish. If you want the KDP fields written to match it, start on our KDP upload and listing prep page.
