ISBNs confuse many new authors because the rules sound more important than they are. An ISBN doesn't protect your copyright, doesn't make a book "official", and isn't required by every store. It's simply the barcode-and-catalogue number the book trade uses to order and track a specific product. This guide explains when you need one, what it costs, and how to use them sensibly.
What an ISBN is, and isn't
| An ISBN is | An ISBN isn't |
|---|---|
| A unique number for one edition and format | Copyright protection |
| How bookshops and libraries order your book | A requirement for every store |
| Linked to a publisher of record | A sign of quality |
| Printed as a barcode on print books | Transferable between different editions |
Your copyright exists as soon as you create the work, whatever the ISBN situation. See publishing under a pen name for how copyright works with pseudonyms.
When you need an ISBN
| Situation | ISBN needed? |
|---|---|
| Ebook on Amazon KDP | No; Amazon assigns its own identifier |
| Ebook on most other stores | Often optional; some aggregators assign one free |
| Paperback or hardcover on KDP | Yes, but KDP can give you one free |
| Print distribution to bookshops and libraries | Yes, usually your own |
| Selling direct from your own website | No |
| BooksOasis, any format | No; optional |
What ISBNs cost
ISBNs are issued by national agencies, one per country. Prices vary a lot.
| United States (Bowker) | Price | Per ISBN |
|---|---|---|
| 1 ISBN | $125 | $125.00 |
| 10 ISBNs | $295 | $29.50 |
| 100 ISBNs | $575 | $5.75 |
A single ISBN is poor value: one book in ebook and paperback already needs two. Most US authors buy the 10-pack. In Canada, ISBNs are free from Library and Archives Canada. Other countries charge anything from nothing to prices similar to Bowker's, so check your own national agency. Buy ISBNs only from your country's official agency or its authorised resellers.
One ISBN per format
Each format is a separate product with its own ISBN:
| Book | ISBNs needed |
|---|---|
| Ebook only | 0 or 1 |
| Ebook + paperback | 1 or 2 |
| Ebook + paperback + hardcover | 2 or 3 |
| Plus audiobook | Add 1 where required |
| A five-book series in three formats | Up to 15 |
The range reflects that many stores don't need an ebook ISBN. A new trim size or a substantially revised edition generally needs a new ISBN; correcting typos doesn't.
Free platform ISBNs vs your own
| Free platform ISBN | Your own ISBN | |
|---|---|---|
| Cost | Free | From $0 to $125 each, depending on country and pack size |
| Publisher of record | The platform or its imprint (for example "Independently published" on KDP) | You or your imprint |
| Use elsewhere | Generally that platform only | Anywhere |
| Best for | A book on one platform | Wide distribution, bookshops, a publishing brand |
For a first book sold mainly on one platform, a free ISBN is usually fine. If you plan to sell the same print edition through several distributors, or want your imprint name on the record, buy your own.
Imprints and the publisher of record
When you buy ISBNs, you register as the publisher, and you can use an imprint name, such as a small press name, instead of your own. That name appears in book trade databases and on retailer pages. Choose one you're happy to keep: it will follow those ISBNs. Pen names and imprints work together, since the ISBN records the publisher while the cover carries the author name.
Large-print and special editions
A large-print edition, a collector's hardcover or an illustrated edition is a different product from the standard book, so each gets its own ISBN. Record it in your register alongside the standard edition so the two are never confused.
Registering your book's details
When you assign an ISBN, you record the book's details with the agency: title, author, format, trim, price and publication date. Keep this information accurate and consistent with what you enter on each store, since retailers and libraries use it to list and order the book. Update it if the price or publication date changes.
Audiobooks and ISBNs
Some audiobook platforms assign their own identifiers and don't require an ISBN; others, and some library distributors, ask for one. If you plan an audiobook, reserve a number for it from your pack, and check the audiobook platform's requirements before you assign it. Like every format, an audiobook ISBN is used for that edition only.
Barcodes
Print books carry the ISBN as a barcode on the back cover. Many print platforms generate the barcode automatically in a reserved area of the cover template. If you create your own, place it where the template's barcode area shows, keep a white box behind it, and don't scale it so small that scanners fail.
Series and box sets
Every book in a series needs its own ISBNs, one per format, and a box set is a separate product with its own ISBN too. For a planned series in several formats, a 10-pack runs out quickly: five books in ebook and paperback already use ten numbers. Authors with a series plan often find the 100-pack cheaper per number in the long run. See how to publish a book series.
Why ISBNs matter for bookshops and libraries
A bookshop or library orders books through trade catalogues, and the ISBN is how they find the exact edition. If you want readers to be able to walk into a shop and order your paperback, or ask their library to buy it, the book needs an ISBN and a listing with a distributor that shops and libraries use. For books sold only online or direct, that matters much less.
Moving a book between platforms
If you started with a free platform ISBN and later want to distribute the same print book more widely, you'll usually need a new ISBN of your own, which makes it a new edition in the catalogues. Reviews and rankings on the original listing may not carry over. That's the main reason authors who plan to go wide buy their own ISBNs from the start.
Three authors, three choices
A first-time novelist publishing an ebook and paperback only on Amazon used no ebook ISBN and KDP's free paperback ISBN, and spent the money on a cover instead.
A small press planning twelve books in three formats bought a 100-pack under its imprint name, so every edition carries its own publisher name and can be distributed anywhere.
A Canadian non-fiction author registered free ISBNs through her national agency and used them on every platform, including a hardcover for libraries.
Keeping an ISBN register
Once you own ISBNs, keep a simple record for each number: the book, format, trim size, edition, publication date and where it's used. It prevents the most common and costly mistake, using the same number twice, and makes updating agency records easy. A spreadsheet is enough.
ISBNs on BooksOasis
On BooksOasis, an ISBN is optional for every format. You can list and sell an ebook, paperback or hardcover without one. If you have an ISBN for a format, you can add it to that edition; our terms require that any ISBN you enter was issued to you for that format, so don't reuse a free ISBN another platform assigned.
- No ISBN required to publish or sell.
- Add your own to any edition.
- Print cover templates include a marked barcode area.
- Unlimited pen names and imprints on every plan.
What BooksOasis does not do
- It doesn't issue or sell ISBNs.
- It doesn't register your book with national ISBN agencies.
- It doesn't distribute to bookshops or libraries, where ISBNs matter most.
A simple ISBN plan
- List your formats for each book: ebook, paperback, hardcover, audiobook.
- Decide where each will sell.One platform, or wide.
- Use free ISBNs where a book lives on one platform, if you're happy with the platform as publisher of record.
- Buy a pack from your national agency for anything distributed widely.
- Keep a register: a simple spreadsheet of each ISBN, its book and format.
Common mistakes
- Buying a single ISBN when a pack costs far less per number.
- Using one ISBN for two formats, such as the paperback and ebook.
- Reusing a platform's free ISBN on another platform.
- Buying from an unofficial reseller whose numbers are registered to someone else.
- Thinking an ISBN is copyright. It is not; copyright exists from creation.
- Forgetting to update the record when the price or date changes.
Sources
Checked September 2026: Bowker: buy ISBNs; Library and Archives Canada: ISBN; BooksOasis: editions and print readiness.
In short
An ISBN is a catalogue number, one per format, and it isn't always required. Use free platform ISBNs for books on a single platform, buy a pack from your national agency when you distribute widely or want your own imprint on the record, keep a register, and never reuse numbers across formats or platforms.
Questions
What is an ISBN?
An International Standard Book Number: a 13-digit identifier for one specific edition and format of a book, used by retailers, libraries and distributors to order and track it.
Do I need an ISBN to self-publish?
Not always. Many stores sell ebooks without one, and some platforms give free ISBNs for print. You need your own ISBN mainly for wide print distribution under your own imprint and for some retailers.
How much does an ISBN cost in the US?
From Bowker, the US agency: $125 for one, $295 for ten, $575 for 100.
Are ISBNs free anywhere?
Yes. Canada issues ISBNs free through Library and Archives Canada, and some other national agencies do too. Check your own country's ISBN agency.
Do I need a different ISBN for each format?
Yes. The ebook, paperback, hardcover and audiobook are separate products, and each needs its own ISBN if you use ISBNs.
What does a free platform ISBN mean?
The platform, or its imprint name, is listed as the publisher of record for that edition, and the ISBN usually can't be used elsewhere. For a book on one platform that's often fine.
Can I use the same ISBN on different platforms?
An ISBN you bought yourself belongs to you and identifies one edition wherever it's sold. A free ISBN assigned by a platform is generally for use on that platform only.
Does an ISBN protect my copyright?
No. Copyright exists when you create the work. An ISBN is only an identifier.
Do I need a new ISBN for a new edition?
For substantial changes, such as a revised text, new format or new trim size, usually yes. Fixing typos generally doesn't need a new ISBN.
Is an ISBN required on BooksOasis?
No. An ISBN is optional for every format. If you add one, it must be an ISBN issued to you for that format.
Does a box set need its own ISBN?
Yes. A box set is a separate product from the individual books, so it needs its own ISBN for each format you publish it in.
How many ISBNs should I buy?
Count your planned books times their formats. One book in ebook and paperback needs up to two; a five-book series in three formats needs up to fifteen. Packs cost far less per number than single ISBNs.
Can bookshops order my book without an ISBN?
Rarely. Bookshops and libraries order through trade catalogues keyed by ISBN, so wide print distribution to them usually needs one.
List with or without an ISBN
On BooksOasis an ISBN is optional for every format.