A practical guide to one of the most important — and most misunderstood — decisions in self-publishing
Before you hit publish on your book, there is one decision that will follow every format you create, every platform you distribute on, and every edition you ever update: the ISBN. Get it wrong and you could find yourself locked out of platforms, forced to unpublish, or starting over from scratch.
In this episode of Easy Peasy Books, Gillian Whitney — business book coach, author, and former librarian — breaks down exactly what an ISBN is, where to get one, what it costs, when you need a new one, and whether using Amazon's free ISBN is the right move for you.
This is not a five-minute topic. There are more decisions involved than most first-time authors realize — and the best time to work through them is before you publish, not after.
What Is an ISBN — and Why Does It Matter?
ISBN stands for International Standard Book Number. It is a 13-digit code (it used to be 10 digits, but the sheer volume of books in the world required an upgrade) assigned to every commercially sold book. Every digit carries meaning: the country issuing it, the publisher, the specific edition, and more.
Think of it the way you would think of a VIN number for a car. Your car's VIN can be looked up to reveal the make, model, year, color, and origin. Thieves know this — which is why the first thing they try to do is scratch or remove it. The ISBN is the same kind of fingerprint for your book.
Inside that one small number sits what the industry calls metadata: the title, subtitle, publisher, publishing date, page count, trim size, format, description, and often a cover image. You can look up any book's metadata on Bowker's Book Wire by typing in its ISBN.
Where to Find an ISBN in a Physical Book
There are two places to look. First, the copyright page — flip to the front matter and you will find it listed there. Second, the back cover — it lives inside the barcode. And that is worth clarifying: the barcode and the ISBN are not the same thing. The ISBN is the number embedded within the barcode.
Do You Actually Need an ISBN?
The short answer is: if you plan to sell your book commercially — on Amazon, in bookstores, on your own website, or through any distributor — yes, you need one. The ISBN is what makes your book discoverable across retail and library systems.
If your book is entirely private — a family history, a gift for clients that will never appear for sale anywhere — you can likely skip it. That said, Gillian is not a lawyer, and this is one area where getting proper advice is worth it if you are unsure.
The Rule That Surprises Every First-Time Author
Here is the part that catches most authors off guard: you need a separate ISBN for every single format of your book.
One book, four formats — paperback, hardback, eBook, audiobook — means four ISBNs. You cannot use the same number for all of them. The moment you start doing the math on pricing, you can see how quickly costs add up.
"You need an ISBN number for every single format of your book. If you're writing one book and you're doing a paperback version, a hardcover, the eBook, and the audiobook — you need a separate ISBN for every single format."
Where to Get an ISBN — It Depends on Where You Live
ISBNs are issued by national agencies, not a single global body. Where you live determines where you go:
- United States and Australia → Bowker (myidentifiers.com)
- United Kingdom and Ireland → Nielsen
- Canada → Library and Archives Canada
- All other countries → search ISBNinternational.org for your country's agency
One important note: it is where you physically live that matters, not your nationality. Gillian is Canadian but lives outside Canada, so she goes through Bowker. Residency, not citizenship, determines your agency.
What ISBNs Actually Cost
This is the part where Gillian admits she fainted — and she is not exaggerating. In the United States, the pricing through Bowker breaks down like this:
- One ISBN: $125
- 10-pack: $295 (approximately $29.50 each)
- 100-pack: available at a lower per-unit rate
If you know you are going to publish multiple books or multiple formats, buying in bulk makes sense. If this is your only book, buying a 10-pack just to save on unit cost is not necessarily the right move.
Pro tip: Amazon has a little-known discount arrangement with Bowker. If you buy through a specific link within KDP, you can purchase a single ISBN for $99 instead of $125. It is buried in the help documentation. Send Gillian a DM if you want to find that link.
Amazon's Free ISBN: The Pros and the Cons
Amazon (through Kindle Direct Publishing) offers a free ISBN for paperback and hardback editions. For Kindle eBooks, no ISBN is required at all — Amazon simply does not ask for one. Neither do Apple Books or Barnes & Noble Press for ebooks, though aggregators like Draft2Digital and IngramSpark do require them.
Gillian used Amazon's free ISBN for her very first book, and she has no regrets. She was not yet ready to commit financially, and it made sense at the time. Here is what you need to know about both sides of that decision.
The Pros of Using Amazon's Free ISBN
- It is genuinely free — no cost for paperback or hardback editions
- Amazon handles registration for you — no metadata entry required on your part
- Available to authors worldwide, not just in the United States
- The book shows as "independently published" on BookWire — not as Amazon-branded
The Cons of Using Amazon's Free ISBN
- You cannot take it with you — the ISBN belongs to Amazon and cannot be used on any other platform
- Amazon is listed as your publisher, not you
- If you later want to move to a different platform using that ISBN, you will need to unpublish, apply for your own ISBN, republish, and then ask Amazon to transfer your reviews to the new listing
"It's like if you came to my house and I made up the spare bedroom for you. When you leave, you can't take my sheets. The sheets belong to the bed. That's what Amazon's ISBN is — it belongs to the platform."
Gillian's recommendation: if you are a first-time author who is unsure whether publishing is going to stick, the free ISBN is a perfectly reasonable starting point. There is no shame in it. You can always change your mind later — it is just more work if you do.
Gillian's Framework: How to Choose Your ISBN Strategy
Before you publish, work through these five questions in order:
Step 1: Decide your commercial intent
Will this book ever be for sale? If yes, you need an ISBN. If it is a private or gift-only book that will never appear in any retail channel, you may be able to skip it.
Step 2: List every format you plan to publish
Paperback, hardback, eBook, audiobook — each one needs its own ISBN. Do this before you go near Bowker or Amazon. Knowing the total number up front helps you decide whether to buy a pack or go one at a time.
Step 3: Decide how much platform flexibility you need
If you are happy publishing exclusively on Amazon for the foreseeable future, the free ISBN is a workable choice. If you want to distribute broadly from day one — through IngramSpark, Draft2Digital, Apple Books, and others — buy your own ISBNs.
Step 4: Choose your publishing imprint name wisely
When you register with Bowker or your national agency, you must set up a publishing imprint. This is the name that will appear as your publisher on every platform. Options include your legal company name, a fictitious press name, or your personal name — though the latter can look less professional in a retail context. Once set, this is difficult to change, and if it is already in a published book, it travels with that book.
Step 5: Track your ISBNs from day one
If you buy a 10-pack, create a simple spreadsheet. Each ISBN is used once, for one format, and cannot be reassigned, resold, or given away. One mistake — like Gillian changing a title after registration — and that ISBN is gone. Good record-keeping prevents expensive waste.
When Do You Need a New ISBN?
Once a book is published, certain changes require a new ISBN. Others do not. This decision tree matters:
Get a New ISBN If You:
- Release a second (or later) edition with substantial new content
- Change the title
- Change the trim size
- Publish in a new language (a Spanish translation of an English book needs its own ISBN)
You Do NOT Need a New ISBN If You:
- Fix typos or make minor corrections (roughly under 10% of content)
- Change the price
- Update the cover design
- Move to a different distribution platform — if you own your ISBN, it travels with you
"ISBNs can't be reused. They can't be sold. They can't be given away. Once it's used for one book, in one format, that's it. They belong to the publisher — and if you self-publish, that publisher is you."
Real Stories from the Episode
Jeff's Book: Being Effective on LinkedIn
Gillian used Jeff Young's book as a live example. Jeff was comfortable with Amazon's free ISBN when he published, and Gillian walked through exactly what would be involved if he ever changed his mind: unpublish, buy a new ISBN, republish, and request that Amazon attach the existing reviews to the new listing. It can be done. It is just work. Knowing that in advance means Jeff made a genuinely informed choice rather than an accidental one.
Tina's Bilingual Publishing Journey
Tina Jarvet published a book in English, then had it translated into Spanish — and each language required its own ISBN. Add in the co-authored book Tina wrote with Gillian, plus eBook and paperback editions of each, and you start to see how the numbers accumulate fast. Tina used Amazon's free ISBNs across her titles and saved significantly as a result.
The Alchemist Has How Many ISBNs?
Out of curiosity, Gillian asked Google Gemini how many ISBNs had been assigned to The Alchemist by Paulo Coelho. The answer was, essentially, impossible to calculate. The book has been reissued multiple times, published in multiple formats, released through multiple publishers, and translated into over 80 languages. Multiply formats by editions by languages by publishers and the number becomes staggering. It is a good illustration of why ISBNs matter at scale — and why the system exists at all.
One More Thing: The Barcode
When you see a barcode on the back of a book, that is not the same as the ISBN. The barcode is a representation of the ISBN, and sometimes it also encodes additional information like a price. The barcode and the ISBN are related but distinct.
Book agencies like Bowker and Nielsen will often try to sell you a barcode as an add-on purchase. You do not need to buy it from them. Amazon can generate one for you, or you can use any number of free barcode generators online. Save your money.
Listen to the Full Episode
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About Gillian Whitney
Gillian Whitney is a business book coach and the host of Easy Peasy Books: From Author to Authority. She helps professionals write and publish books that build credibility, attract the right clients, and establish lasting expertise. Learn more at easypeasybooks.com