Ebooks

What is an AZW3 file?

Updated Jul 2026

Definition

AZW3, also called Kindle Format 8, is the ebook file format Amazon uses for Kindle books and personal documents. It supports richer layout than older Kindle formats, including embedded fonts and fixed positioning for things like comics and textbooks. The catch is that it's built around the Kindle ecosystem, so most other e-readers can't open it without converting it first.

AZW3Kindle Format 8

Extension: .azw3
Type: Ebooks
Typically: Kindle

Why AZW3 exists

Amazon introduced AZW3 in 2011 alongside the Kindle Fire, as a replacement for the older AZW format. It was built to handle content that plain reflowable text couldn't: children's books with illustrations, comics, and textbooks that need elements to stay in a fixed place on the page.

Under the hood, AZW3 borrows a lot from EPUB, using HTML and CSS style formatting wrapped in Amazon's own container. That's how it manages embedded fonts and more detailed typography than older Kindle formats allowed, while still working with Kindle's syncing features like bookmarks and reading position across devices.

People run into AZW3 mainly when they want to read a Kindle file somewhere other than a Kindle app or device, such as a Kobo e-reader or another reading app. Since most of those don't recognize AZW3 natively, the usual fix is converting it to EPUB or PDF.

The trade-offs

Strengths

Supports fixed layouts for comics, textbooks, and illustrated books
Embeds fonts and finer typography than older Kindle formats
Syncs bookmarks, highlights, and reading position across Kindle apps

Watch-outs

Not read natively by most non-Kindle e-readers
Books bought from the Kindle store are often DRM protected
Needs converting to EPUB or PDF for wider compatibility

A note on privacy

An AZW3 file can carry your reading data along with it, including bookmarks, highlights, and how far you've read. Uploading it to an online converter sends that personal reading history to a server you don't control. Converting it on your own computer keeps the book and your notes on your machine the whole time.

Convert an AZW3 file

Questions

How do I open an AZW3 file?

It opens natively in the Kindle app or on a Kindle device. On other e-readers, like a Kobo, you'll usually need to convert it to EPUB first.

Is AZW3 better than EPUB?

AZW3 supports more advanced formatting, like fixed layouts and embedded fonts, but EPUB is readable on far more devices and apps. Which is better depends on what you need it for.

Why does my Kindle save books as AZW3?

It's Amazon's native format for Kindle content, built to support layouts and typography that older Kindle formats couldn't handle.

Can I convert AZW3 without uploading it?

Yes. A desktop app like Morphjet converts AZW3 on your own computer, so the file and your reading data never leave your machine.

Can I convert a book I bought from the Kindle store?

Many purchased Kindle books have DRM protection that blocks conversion no matter what tool you use. Personal documents and DRM-free files convert without issue.

Morphjet opens and converts AZW3 and 1,800+ other formats, all on your own computer. Launching this July.