ASIN, KDP Number, and ISBN Explained: A Simple Guide for New Authors
If you're publishing your first book on Amazon Kindle Direct Publishing (KDP), you'll quickly discover that your book seems to have several different identification numbers.
There's an ASIN, a KDP Number, and sometimes an ISBN.
So... which one actually matters?
The good news is that each number serves a different purpose. Once you understand what they are, it's actually very simple.
Let's break it down.
The ASIN
ASIN stands for Amazon Standard Identification Number.
Think of it as your book's unique Amazon ID.
Every Kindle eBook published on Amazon automatically receives its own ASIN.
For example:
More Than We Needed
ASIN: B0H123XXXX
Whenever someone searches for your eBook on Amazon, this is the number Amazon uses to identify it.
Important
Every Kindle eBook has one unique ASIN.
If you later publish a paperback or hardcover edition, those editions will receive different identifiers.
The KDP Number
This is the one that confuses many new publishers.
Every title you create inside your KDP Bookshelf receives an internal KDP identifier.
It might look something like:
6PPABD6XXXX
or
TS5JAS5XXXX
Unlike an ASIN, readers will almost never see this number.
It is used internally by Amazon KDP to identify your publishing project.
When you contact KDP Support, they will often ask for either:
your ASIN
your KDP Book ID
Both identify the same publishing project inside Amazon's system.
Think of it like this
ASIN = Amazon's public book ID
KDP Number = Amazon's internal project number
The ISBN
ISBN stands for International Standard Book Number.
Unlike an ASIN, ISBNs are used across the entire publishing industry—not just Amazon.
Bookstores...
Libraries...
Distributors...
Retailers...
...all use ISBNs.
An ISBN identifies a specific edition of a book.
For example:
Kindle eBook
Paperback
Hardcover
Large Print
Audiobook
Each edition is considered a different product.
That means each edition requires its own ISBN (where ISBNs are used).
Does a Kindle eBook Need an ISBN?
No.
Amazon Kindle eBooks do not require an ISBN.
Instead, Amazon assigns an ASIN automatically.
Many publishers never purchase ISBNs for their Kindle editions.
Paperbacks and Hardcovers
Printed books usually use ISBNs.
When publishing through KDP you have two options:
Option 1 – Free Amazon ISBN
Amazon provides a free ISBN for your paperback or hardcover.
Advantages:
Completely free
Quick and easy
Perfect for many self-publishers
Disadvantage:
The publisher listed will be Amazon rather than your own publishing company.
Option 2 – Buy Your Own ISBN
Many independent publishers purchase their own ISBNs.
Advantages:
Your publishing company appears as the publisher.
You retain greater publishing flexibility.
The ISBN can be used with multiple distributors.
Owning your own ISBN block creates a more professional publishing catalogue.
Does Every Format Need a Different Number?
Yes.
Each edition is treated as a separate product.
For example:
| Edition | Identifier |
|---|---|
| Kindle eBook | ASIN |
| Paperback | ISBN |
| Hardcover | ISBN |
| Audiobook | ISBN (if assigned by the distributor) |
Even though the story is identical, each format is considered a different product.
A Real Example
Imagine Palmista Press publishes More Than We Needed.
The identifiers might look like this:
Kindle eBook
ASIN: B0HXXXXXXX
KDP Number: 6PPABD6XXXX
Paperback
ISBN: XXX-1-23456-001-1
Different KDP Number
Hardcover
ISBN: XXX-1-23456-002-8
Different KDP Number
Three editions.
Three different products.
Three different identifiers.
Which Number Should You Keep in Your Records?
At Palmista Press we recommend recording all three where applicable.
For every published title, keep a simple spreadsheet with:
Book title
Series
Author
ASIN (eBook)
Paperback ISBN
Hardcover ISBN
KDP Number(s)
Publication date
Having everything in one place makes publishing, updating metadata, and contacting KDP Support much easier.
Final Thoughts
The different identification numbers can seem confusing when you're publishing your first book, but each has a clear purpose.
ASIN identifies your Kindle eBook on Amazon.
KDP Number identifies your publishing project inside Amazon KDP.
ISBN identifies printed editions across the global publishing industry.
Once you understand the difference, managing your publishing catalogue becomes much easier.
Whether you're publishing your first novel or building a catalogue of hundreds of books, keeping accurate publishing records is one of the best habits you can develop.
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