How to Get an ISBN for Your BookEverything Authors Need to Know in 2026

What an ISBN Actually Is

An ISBN — International Standard Book Number — is a 13-digit unique identifier assigned to each distinct edition and format of a book. Retailers, libraries, distributors and catalogues worldwide use ISBNs to identify, order and track books. Without an ISBN, a print book cannot be ordered by bookshops, stocked by libraries or listed in international wholesale catalogues.

ISBNs were not originally designed for the digital era. eBooks on Amazon use Amazon's own ASIN system instead. But for any physical format — paperback, hardcover — and for global distribution beyond Amazon, an ISBN is essential infrastructure.

Free KDP ISBN: What It Is and What It Limits

Amazon KDP offers a free ISBN for print books published through the platform. This ISBN works perfectly well for Amazon distribution. The limitations are two: first, the ISBN lists Amazon KDP as the publisher of record, not you or your imprint. Second, this ISBN cannot be used on IngramSpark or any other distribution platform. If IngramSpark is part of your distribution plan — which it should be for any author wanting bookshop and library reach — a free KDP ISBN is insufficient.

The free KDP ISBN is appropriate for authors publishing exclusively on Amazon with no intention of pursuing bookshop or library distribution. For most serious publishing projects, a purchased ISBN is the better long-term decision.

Purchased ISBN: Where to Buy and What It Costs

In the United States, ISBNs are purchased exclusively from Bowker at myidentifiers.com. Pricing: $125 for a single ISBN, $295 for a block of 10, $575 for 100. If you plan to publish multiple formats or multiple titles, buying in a block is significantly more cost-effective.

In the United Kingdom, ISBNs are purchased from Nielsen at isbn.nielsenbook.co.uk. Pricing: £89 for one, £164 for 10. In Canada, ISBNs are assigned free of charge through Library and Archives Canada. In Australia through Thorpe-Bowker, free for Australian publishers.

A purchased ISBN allows you to list yourself or your imprint as the publisher on every platform. This matters for authors building a long-term publishing brand — the publisher name appears on Amazon, in library catalogues and in IngramSpark's wholesale database.

How Many ISBNs Does Your Book Need?

Each distinct format requires a separate ISBN. A book published in four formats needs four ISBNs: one for the paperback, one for the hardcover, one for the eBook (optional but recommended for wide distribution beyond Amazon), and one for the audiobook. A revised edition requires a new ISBN even if the content is substantially the same. A new cover on the same edition does not require a new ISBN.

For a two-format launch (paperback and Kindle), you technically need only one purchased ISBN for the paperback (Amazon provides a free ASIN for the Kindle edition). For a full four-format launch with IngramSpark distribution, plan for two to four purchased ISBNs.

ISBN and IngramSpark

IngramSpark requires that every title submitted use either a purchased ISBN or an IngramSpark-assigned ISBN (which IngramSpark provides for a fee as part of their setup). A free KDP ISBN is not accepted on IngramSpark. This is one of the most common setup errors that causes self-published books to appear on IngramSpark's catalogue but remain effectively un-orderable by bookshops and libraries.

For the full IngramSpark setup requirements including wholesale discount settings and returns policy configuration, see the print on demand distribution guide. For the complete Amazon KDP setup, see the Amazon self-publishing guide.

ISBNs in Professional Publishing Packages

Most professional publishing services include ISBN registration as part of their package. Columbia Publication handles ISBN registration, platform submission and metadata configuration as part of every publishing engagement — ensuring the correct ISBN type is used for each distribution channel from the start. See full publishing service details.

Frequently Asked Questions