An ISBN, International Standard Book Number, is a 13 digit number that identifies one specific edition of one specific book. Not your book in general. One edition of it. Your paperback has one ISBN, your hardcover has another, your ebook has another, and your audiobook has another, because shops, libraries, and distributors use the number to know exactly which version a customer is ordering.
Think of it as a passport for a single format of your book. Without one, most bookstores and libraries simply cannot stock or order that edition. An ISBN does not protect your copyright, does not prove you wrote the book, and does not make your book official. It is an identification and ordering tool, and a very important one.
Do You Even Need an ISBN?
It depends on the format and where you want to sell:
- Kindle ebooks on Amazon: no ISBN required. Amazon gives the book its own internal number, called an ASIN, for free.
- Print books (paperback and hardcover): yes, practically speaking. You can use a free one from the platform or buy your own, but a print edition needs an ISBN to be ordered by stores and libraries.
- Ebooks outside Amazon (Apple Books, Kobo, and others): usually yes, one ISBN for the ebook edition.
- Audiobooks: yes, the audio edition gets its own ISBN if it is distributed to libraries and audiobook stores.
The Big Decision: Free ISBN or Buy Your Own?
Almost every publishing route offers you a free ISBN. It costs nothing and works instantly. So why do authors pay for their own?
Publisher of record. Whoever owns the ISBN is listed as the publisher of that edition. With a free ISBN from a platform, the platform is listed as your publisher. With your own ISBN, you, or your own publishing name, are listed as the publisher. Many authors happily use free ISBNs for their first book. Authors building a long term catalogue usually prefer their own.
Moving your book. An ISBN can never be transferred or reused. If you publish your paperback with a free platform ISBN and later want to move that exact edition elsewhere, you cannot take the number with you. You would publish a new edition with a new ISBN, which splits your sales history and reviews setup across two listings.
Control of the data. The ISBN owner controls the book data attached to the number: title, author, description, and price information that flows to stores and libraries worldwide.
Neither choice is wrong. The mistake is choosing without knowing the difference.
How to Get an ISBN, Step by Step (United States)
In the US, ISBNs are sold by one official agency: Bowker, at isbn.org.
Step 1: Decide how many you need. Count your formats. One paperback = 1. Paperback + hardcover + ebook + audiobook = 4. Most authors who plan a series or multiple formats save a lot by buying a block.
Step 2: Buy the ISBN or the block. At the time of writing, one ISBN costs $125, and a block of 10 costs $295. That is $29.50 per number instead of $125, which is why the block is the smart buy for anyone publishing more than two formats. Prices change, so check the official site before you buy.
Step 3: Create your account and register your publishing name. This name appears as the publisher of record, so choose it like a brand, not an afterthought.
Step 4: Assign an ISBN to your book. In your Bowker dashboard, you enter the title, author, format, and publication date for the edition, and assign one number to it. One number, one format, forever.
Step 5: Get the barcode. Print books need a barcode on the back cover, generated from the ISBN, usually with the price encoded in it. Bowker sells barcodes, and many cover tools, including Folio's Cover Studio workflow, place the barcode area correctly when your cover is prepared for print. Never type an ISBN into a barcode generator from a random website and trust the result without testing it.
Step 6: Put the ISBN in the book. Print editions carry the ISBN on the copyright page and in the barcode on the back cover. Ebooks carry it on the copyright page and in the store metadata.
What About Other Countries?
ISBNs always come from your own country's agency, and the price varies wildly:
| Country | Agency | Cost |
|---|---|---|
| United States | Bowker | $125 for one, $295 for ten |
| United Kingdom | Nielsen | Sold in blocks, from around £93 for one |
| Canada | Library and Archives Canada | Free |
| India | Raja Rammohun Roy National Agency | Free |
| Australia | Thorpe-Bowker | Sold singly and in blocks |
If ISBNs are free in your country, always get your own. If they are paid, the free versus own decision above is the one that matters.
Five ISBN Mistakes That Cost Authors Money
- Reusing one ISBN for two formats. A paperback and an ebook with the same number corrupts both listings.
- Using a new ISBN for a tiny fix. Correcting typos does not create a new edition. A substantially revised book does, and needs a new ISBN.
- Buying one at a time when you need four. The block of 10 exists for exactly this reason.
- Putting the free ISBN decision off until launch day. Decide before your cover is made, because the barcode belongs on the cover.
- Believing an ISBN protects your copyright. It does not. Your copyright exists the moment you write the book.
How Folio Handles Your ISBN
When you publish through Folio Authors, the ISBN choice sits right inside the publishing flow, at the step where you add your book details. You can take a free ISBN from Folio and be selling within days, or use your own ISBN if you bought one and want to be listed as the publisher of record. Either way, your book is published in your name, at prices you set, and your rights stay 100% yours.
If you are unsure which way to go, start with the free assessment of your book on the Free plan and decide about the ISBN when your book is actually ready. The number is a launch detail, not a writing detail.
Frequently Asked Questions
How much does an ISBN cost?
In the US, $125 for a single ISBN or $295 for a block of 10 from Bowker. In some countries, including Canada and India, ISBNs are free from the national agency.
Can I get an ISBN for free?
Yes. Platforms like Amazon KDP and Folio Authors offer free ISBNs. The trade off is that the platform is listed as the publisher of record for that edition, and the number cannot move with the book later.
How many ISBNs do I need for one book?
One for each format: paperback, hardcover, ebook, and audiobook each need their own. A book released in all four formats needs four ISBNs.
Do I need an ISBN for a Kindle ebook?
No. Amazon does not require one for Kindle ebooks and assigns its own ASIN instead. You only need an ISBN for the Kindle edition if you want one attached to it for other channels.
Can I use the same ISBN for a revised edition?
No. A substantially revised edition is a new edition and needs a new ISBN. Small corrections like typo fixes do not.
The Bottom Line
An ISBN is a small number with a long shadow. Get the decision right once, free or your own, per format, before your cover is printed, and it will never bother you again. Buy in a block if you are in the US and plan more than two formats. And remember that the ISBN is one line in your whole launch: if you want the rest of the launch handled in the same place, Folio Authors takes your book from manuscript to live listing, ISBN included, with your rights untouched.
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