AZW3, EPUB, MOBI, or PDF: Which Format to Use on Kindle

13/10/2026

Choosing the right file format for your Kindle depends on how you transfer files and the reading experience you want. AZW3, EPUB, MOBI, and PDF all act differently, so here's what you need to know before picking one.

Format	Reflowable Text	Via Cable	Send to Kindle	Best For
AZW3	Yes	Yes	No	Kindle’s native format. Best for transferring by cable.
EPUB	Yes	No	Yes	Open standard. Best for sending over the internet or other readers.
PDF	No	Yes	Yes	Fixed pages. Good for viewing graphics, not ideal for reading long texts.
MOBI		Some old files	No	Old format. Avoid for new files.

How Does AZW3 Work?

AZW3 (also known as KF8) is the main Kindle format. It supports adjustable fonts, a table of contents, and images. You transfer AZW3 files by connecting your Kindle with a cable and copying the file to the documents folder. Learn more about transferring files by cable. Send to Kindle does not accept AZW3 files.

What About EPUB?

EPUB is the standard ebook format for most readers besides Kindle. Kindle won’t open EPUB files if you copy them by cable, but Send to Kindle accepts EPUB and converts it. The result is a Kindle book with its table of contents intact.

Is PDF Good for Kindle?

PDFs appear as fixed pages on Kindle, shrinking the whole page to fit the screen. This works for graphics, but isn’t comfortable for reading long texts. If you want a better reading experience, convert the PDF first. See how to send a PDF to Kindle without needing to zoom for tips.

Should You Use MOBI?

MOBI is an old Kindle format. Amazon no longer supports it through Send to Kindle. Older MOBI files still work if you transfer them, but for new books, use AZW3 or EPUB.

Choosing the Right Format

If you transfer by cable: Use AZW3.
If you send over the internet: Use EPUB.
If you use a different brand of reader: Use EPUB.
If you have a PDF: Convert it first. Legible can convert PDFs and comics to Kindle formats, letting you preview the result and download in AZW3 or EPUB.