An ISBN is a 13-digit number that identifies one edition of one book. You do not need one to publish an ebook on Amazon, but you will want one if you plan to sell a printed book beyond Amazon. This guide explains what an ISBN does, where to get one and the mistakes to avoid.
What an ISBN is
ISBN stands for International Standard Book Number. The current format has 13 digits, and the number identifies a specific edition and format of a specific title. Libraries, wholesalers and bookshops use it to find the right book without confusion between editions.
The number is linked to a record that holds the title, author, publisher, format, price and publication date. Keeping that record accurate is part of the job of whoever owns the ISBN.
When you need one
- Printed book sold through bookshops, libraries or wholesalers: yes, in practice they will not list a book without one.
- Printed book sold only on Amazon: Amazon will assign a free ISBN, or you can use your own.
- Kindle ebook on Amazon: no. Amazon uses its own identifier, called an ASIN.
- Ebooks on other stores: some require an ISBN and some do not, so check each store.
- Audiobook: usually a separate ISBN if you want it listed in trade catalogues.
Each format is a separate product. A paperback, a hardback and an ebook of the same book use different ISBNs if they are sold through channels that ask for them.
The free ISBN from KDP
KDP will give you a free ISBN for a paperback or hardback. It costs nothing and is quick, but it comes with limits. The publisher of record is listed as Amazon’s imprint and not you, and the number cannot be used with other printers or distributors. If you ever want to move to IngramSpark or another channel, you will need a new ISBN and a new edition record.
Many authors who plan to sell widely buy their own ISBN for this reason. If you are certain that Amazon is the only place you will ever sell the printed book, the free number is a reasonable choice.
Where to get your own
ISBNs are issued by one national agency per country, and buying from the official agency means you are named as the publisher of record.
- United Kingdom and Ireland: Nielsen ISBN Agency.
- United States: Bowker, through its Identifiers service.
- Canada: free through Library and Archives Canada for eligible Canadian publishers.
- Australia and New Zealand: Thorpe-Bowker.
Buying a block of ten is normally far cheaper per number than buying one at a time, which matters if you plan several formats or more than one book. Be wary of third-party resellers offering single numbers cheaply. The record may name the reseller as publisher, which defeats the point.
When a book needs a new ISBN
- A new format, such as moving from paperback to hardback.
- A new edition with substantial changes to the text, the title or the page count.
- A change of publisher.
You do not need a new ISBN for correcting typos, changing the price or updating the cover while the edition stays the same.
The barcode
The barcode on the back of a printed book is an EAN-13 barcode generated from the ISBN. Retailers scan it at the till and in their warehouses. Most printers and platforms can generate one for you, and your cover designer needs to leave a clear, correctly sized area for it. If the cover wrap is made before the ISBN is known, ask the designer to leave a placeholder and drop the real barcode in later.
Legal deposit in the UK
This is separate from the ISBN. UK law requires publishers of printed books to send one copy to the British Library within one month of publication, and the other legal deposit libraries can request copies too. You do not need an ISBN to be covered by the rule. If you publish in the UK, it is worth checking the current requirements for your edition.
Common mistakes
- Using one ISBN for several formats or editions.
- Buying from a reseller and finding the wrong publisher on the record.
- Printing the barcode before the ISBN is final.
- Letting the book’s metadata go out of date, so the title or price differs between retailers.
- Forgetting that a free KDP ISBN cannot be moved.
If you would like us to handle the ISBN, barcode and retailer set-up in your own name, see our self-publishing service. For a view of how the two main print platforms differ, read KDP or IngramSpark, and if your cover is still to be made, our guide to what a book cover costs explains the barcode and bleed it needs.
