How to Get an ISBN for Your Book: A Complete Guide
An ISBN is one of those publishing details that sounds more complicated than it is — but the decision behind it genuinely matters, because it affects who is listed as your book's publisher and where it can be sold. This guide explains what an ISBN is, whether you actually need one, and exactly how to get it.
For the wider process, see our guide on how to self-publish a book.
What an ISBN actually is
An ISBN (International Standard Book Number) is the unique 13-digit identifier that bookstores, libraries, and retailers use to catalog and track a specific edition of a book. Every format and edition needs its own — your paperback, hardcover, and ebook each require a separate ISBN, because they are distinct products.
Do you actually need one?
Not always, which surprises people:
- Ebooks on Amazon Kindle do not require an ISBN — Amazon assigns its own internal identifier (an ASIN). Other ebook retailers may prefer one.
- Print books effectively need an ISBN to be sold and cataloged, but your publishing platform can supply one for free.
- Bookstore and library distribution and publishing under your own imprint make owning your ISBN much more worthwhile.
Your options: free vs paid
This is the real decision:
- A free ISBN from your publishing platform (like Amazon KDP) costs nothing, but the platform is listed as the publisher of record. Perfectly fine for many self-publishers, especially those selling primarily on that platform.
- Your own ISBN, purchased from the official agency in your country, lists you or your imprint as the publisher. This gives you control, a professional appearance, and portability across platforms — the same ISBN follows your book everywhere.
How to buy your own ISBN
ISBNs are issued by an official national agency, which varies by country — in the United States it is Bowker, and other countries have their own designated agency. You buy directly from that agency (or an authorized reseller). They are sold singly or, more economically, in blocks — if you plan to publish several books or multiple formats, a block brings the per-ISBN cost down substantially. (ISBN prices and the issuing agency depend on your country; check your national agency's current pricing before buying.)
How to assign it
Once you have your ISBN, you enter it in your publishing platform's setup for that specific format, rather than accepting the free one. Use a different ISBN for each format and edition — one for the paperback, one for the hardcover, one for the ebook if you choose to assign one.
Free or your own — which should you choose?
- Take the free platform ISBN if you are publishing mainly on one platform, keeping things simple, and not focused on bookstore distribution or building an imprint.
- Buy your own if you want to publish under your own imprint, distribute through multiple channels or into bookstores and libraries, or present the most professional face. Our guide on KDP vs IngramSpark is relevant here, since wider distribution is where your own ISBN pays off.
The bottom line
An ISBN identifies a specific edition of your book, and every format needs its own. You can take a free one from your publishing platform — fine for many authors — or buy your own to publish under your imprint and keep it portable across every channel. For a single-platform ebook you may not need one at all; for a print book with bookstore ambitions, owning your ISBN is worth it.
Frequently asked questions
What is an ISBN and what does it do?+
An ISBN is a unique 13-digit identifier that bookstores, libraries, and retailers use to catalog and track a specific edition of a book. Every format and edition — paperback, hardcover, ebook — needs its own separate ISBN.
Do I need an ISBN to self-publish?+
Not always. Amazon Kindle ebooks use Amazon's own identifier instead, so no ISBN is required there. Print books effectively need one to be sold and cataloged, but your platform can provide it free.
Should I use a free ISBN or buy my own?+
A free platform ISBN is fine if you publish mainly on one platform and keep things simple, but it lists the platform as publisher. Buying your own lists you or your imprint as publisher and stays with your book across every platform — better for bookstore distribution and building a brand.
How much does an ISBN cost?+
It depends on your country's issuing agency and whether you buy singly or in a block, with blocks bringing the per-ISBN cost down considerably. Check your national agency's current pricing, since it varies by country.
Where do I buy an ISBN?+
From the official ISBN agency in your country — for example, Bowker in the United States, with other countries having their own designated agency. Buy directly from that agency or an authorized reseller.
Do I need a separate ISBN for each format?+
Yes. Your paperback, hardcover, and ebook are distinct products and each needs its own ISBN. A new edition with significant changes also needs a new one.
Do I need an ISBN for a Kindle ebook?+
No. Amazon assigns its own identifier to Kindle ebooks, so an ISBN is not required. You can still assign your own if you want consistent identification across other retailers.
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