Understanding the Difference Between ISBN Numbers for Print and eBooks
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By PAGE Editor
One of the most frequent points of confusion for a new self-published author is the ISBN Number. After navigating the process of buying one (or a block of 10), you're faced with a new question: "I have my paperback's ISBN. Can I just use that same number when I upload my eBook file?"
The answer is an immediate and resounding no.
Using the same ISBN Number for different formats is a critical error that will break your book's distribution. To understand why, you have to stop thinking of your "book" as one thing. In the eyes of the global retail supply chain, your book is a product, and different versions are different products.
The Core Principle: One Format = One ISBN
An International Standard Book Number (ISBN) is, at its heart, a product identifier. Its job is to tell a retailer, distributor, or library exactly what product a customer is ordering.
Think of it like this: You wouldn't expect a car dealership to use the same Vehicle Identification Number (VIN) for the 2-door coupe and the 4-door sedan, even if they are the same "model." They are different products with different specifications and prices.
The same applies to your book:
Your Paperback: This is a physical object with a specific trim size (e.g., 6x9), page count, and cover finish (matte/glossy). It has a physical shipping weight.
Your Hardcover: This is a different physical object. It has a different trim size, a different cover type (case laminate or dust jacket), and a different shipping weight. It also has a different price.
Your eBook: This is a digital file (likely an .ePub or .mobi). It has no weight, no pages, and no physical dimensions. It is delivered instantly via download.
If you used the same ISBN Number for all three, the system would collapse. A customer at Barnes & Noble's website would order what they think is the paperback, but the system wouldn't know whether to ship them a physical book or email them a download link.
Therefore, the rule is simple: Every unique format of your book must have its own unique ISBN.
A Practical Example
Let's say you've written a novel called The Crimson Key. To distribute it widely in 2025, you will need, at minimum, three separate ISBNs from your block of 10:
ISBN 978-1-99999-01-1 (Assigned to: The Crimson Key, Paperback, 6x9)
ISBN 978-1-99999-01-2 (Assigned to: The Crimson Key, Hardcover, 6x9)
ISBN 978-1-99999-01-3 (Assigned to: The Crimson Key, eBook, ePub)
When you upload your files to a distributor like IngramSpark, you will enter the paperback ISBN in the paperback project and the hardcover ISBN in the hardcover project. When you upload to an eBook aggregator like Draft2Digital, you will provide the eBook ISBN.
The Special Case: Kindle and the ASIN
This is where it gets slightly confusing. If you only plan to sell your eBook on Amazon's Kindle platform, you technically do not need an ISBN Number for it.
Amazon uses its own internal tracking code called an ASIN (Amazon Standard Identification Number). When you upload your Kindle-formatted file to KDP (Kindle Direct Publishing), Amazon assigns it an ASIN for free. This ASIN is how your eBook is tracked within the Amazon ecosystem. However, this ASIN is not an ISBN. It is not transferable and has no meaning to any other retailer, like Apple Books, Kobo, or Barnes & Noble.
This leaves you with a choice:
Go Amazon-Exclusive (KDP Select)
Upload your eBook to KDP, don't enter an ISBN, and let Amazon assign an ASIN. This is free and simple, but it locks your eBook to Amazon for the duration of your KDP Select term.
Go Wide
Buy your own ISBN Number and assign it to your eBook. You can still upload it to KDP (you'll enter your own ISBN in the setup field), and Amazon will also assign it an ASIN, but the two will be linked. You can then take that same eBook file (and its ISBN) to Kobo, Apple, and all other stores. This is the only way to have your eBook appear in multiple retail storefronts.
Frequently Asked Questions
Do different eBook files (ePub, MOBI, PDF) need different ISBNs?
Technically, the international ISBN standard says yes. In practice, the 2025 self-publishing industry standard is to use one ISBN Number for all "eBook" versions. You assign your ePub file an ISBN, and you use that same ISBN when uploading to KDP (which converts it to MOBI) and other stores.
What if I fix typos? Do I need a new ISBN?
No. Minor corrections (typos, grammar) or changing the cover design do not require a new ISBN Number. It's still the same core product.
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