Every published book carries a unique identification number known as an ISBN. If you're publishing your first book, you've probably come across the term already and wondered whether you need one, where to get one, or why different editions require different ISBNs.
This guide explains ISBNs in straightforward language, helping you understand what they are, when you need one, and how they fit into the self-publishing process.
ISBN stands for International Standard Book Number.
It uniquely identifies a specific edition of a book.
Booksellers, distributors, libraries, and online retailers use ISBNs to identify books accurately.
Every format of a book (paperback, hardback, eBook) is treated as a separate product and therefore usually requires its own ISBN.
✔ Publishing a printed paperback
✔ Publishing a hardback
✔ Selling through bookshops
✔ Distributing through libraries
✔ Using IngramSpark
✔ Publishing only a Kindle eBook through Amazon KDP
✔ Publishing privately for family or friends
Free vs Purchased ISBNs
Advantages
No upfront cost
Quick to obtain
Ideal for first books
Disadvantages
The platform is normally listed as the publisher.
Less flexibility if you later change platforms.
Advantages
You remain the publisher.
Greater flexibility.
Better for building a publishing brand.
Disadvantages
Initial purchase cost.
ISBNs are supplied by the national ISBN agency, Nielsen.
Single ISBNs or blocks of ISBNs can be purchased.
Many first-time authors begin with the free ISBNs offered by publishing platforms before deciding whether purchasing their own ISBNs suits their long-term goals.
Different Formats Need Different ISBNs
Book Format
Paperback
Hardback
eBook (EPUB)
Kindle eBook (Amazon KDP)
Audiobook
ISBN Required?
✔ Yes
✔ Yes
Usually Yes
Often No (Amazon uses its own ASIN)
✔ Usually Yes
Frequently Asked Questions
Can two books share the same ISBN?
No. Every edition and format has its own unique ISBN.
Can I reuse an ISBN?
No. Once assigned, an ISBN remains permanently linked to that specific edition.
Does changing the cover require a new ISBN?
Usually not. Significant changes to the content or format may require a new ISBN, but a simple cover redesign generally does not.
Should I buy my own ISBNs?
If you're planning to publish several books under your own publishing imprint, purchasing your own ISBNs can be worthwhile. For many first-time authors, however, a free ISBN provided by a publishing platform is often a perfectly suitable place to start.
Choosing the right ISBN option is only one part of publishing your book. If you'd like personal guidance on ISBNs, formatting, or preparing your manuscript for publication, I'd be delighted to help.
Explore My Publishing Services. Contact Samuel Fenwick Publishing at samuel@samuelfenwick.com