Your ebook File Format

If you’ve recently uploaded an ebook to your KDP dashboard, you may have noticed a change. Amazon now recommends providing an EPUB file for publishing instead of a file in their proprietary MOBI format.

If your MOBI file contains reflowable content (i.e. text-heavy books), they recommend you upload an EPUB file instead. It’s not mandatory yet!

Before uploading, validate your file with Kindle Previewer. Although MOBI files are still supported, if you open your book file in Kindle Previewer, you will see a pop-up warning

“We recommend using EPUB format for publishing new books and updating previously published titles.”

Kindle Recommended and Supported Formats

More information from Kindle about formats.

(Thanks to the guys over at Vellum for bringing this to my attention.)