What’s an ISBN Number?

If you are thinking about, or even actually writing, and/or self-publishing a book, there are very many different aspects you need to consider. If you are intending to market and sell your work through any form of retail outlet or channel, then one of these things is the acquisition and allocation of an ISBN number.

Here are the basic details you need to be aware of regarding ISBN numbers:

ISBN numbers – The headline details

First, and most basic question – what does ISBN actually stand for? International Standard Book Number is the answer – it is a unique numeric identifier for any commercial book.

This number is universally used to identify, order, track and list one-off publications worldwide. Its’ current form has a standardised thirteen digit format, and is comprised of five different components.

These components are:

  1. EAN Prefix – 3 digits to make the ISBN compatible with international barcodes
  2. Registration Group – 2 digits identifying the country or region of publishing origin
  3. Registrant – 5 digits identifying the publisher
  4. Publication – 2 digits showing the number assigned to a particular edition and format
  5. Check Digit – A final, single digit mathematically generated to validate the ISBN

Why is an ISBN number required?

Whilst it is not a legal requirement to assign an ISBN number to your publication, nearly all bookstores and retail outlets and channels work by using an electronic point-of-sale system, which are reliant on ISBN’s and barcodes to operate – if your book does NOT have an ISBN , these outlets CANNOT sell it!

It is likely that your book will require multiple ISBNs throughout its’ retail life, as each edition is assigned a different number. This means that, if you want to market your book in multiple formats – paperback, hardback, e-book, limited edition etc. – each format will require a unique ISBN.

Obtaining an ISBN number

To get an ISBN number you will need to register as a self-publisher with the National ISBN agency in your country or region – this information can be found through the International ISBN Agency website.

Once registered, you will be assigned a Registrant Code, from which you can then purchase ISBNs in batches of different quantities. Ensure that you carefully record and track any ISBNs you submit.

Your ISBN numbers need to be encoded into a machine-readable format barcode that will be clearly displayed on every copy of your book. These barcode generators are available, often for free, online.      

More useful ISBN information

  • Once a set of ISBNs has been purchased, they are valid for life – you DO NOT need to renew them!
  • An ISBN number DOES NOT represent ownership of copyright of the book. It DOES, however, greatly help in any argument over breach of copyright disputes and is, therefore, worth submitting a listing to the international ISBN database.
  • Whilst e-books are not marketed via point-of-sale systems, therefore technically not requiring an ISBN, no other form of retail channel will be able to sell your book without one, so any interest garnered from online sales can’t be transferred to printed editions, if anyone should want to purchase that way. It is always beneficial to get an ISBN number for ALL formats of your book!


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