An Explanation of E-Book Formats


If you are a self-published author or someone looking to do e-book conversions, it can feel daunting at first because there are so many different formats to worry about. The two main formats, however, are EPUB and Kindle’s proprietary format. EPUB can be used and read on Apple, Nook, Kobo, Sony, Google, and more devices, and Kindle’s format can only be read on Kindle devices. Here’s a breakdown of the EPUB and Kindle formats and what that means for developers and publishers:


EPUB comes in two flavors: EPUB2 and EPUB3. EPUB3 was introduced in 2011, though currently not all devices support all its features. However, there are rumors that EPUB3 will become more widely available beginning this year.

MPS blog has a great chart that breaks down the capabilities of an EPUB2 file versus an EPUB3 file. Basically, EPUB3 has more flexibility when it comes to styling a book, such as colors of text and embedded fonts, as well as read aloud functionality, and audio and video. IDPF released a spec that outlines the changes from EPUB2 to EPUB3, and you can find examples of EPUB3 files at Azardi and Google. IDPF also explains the backwards compatibility of EPUB3 with EPUB2, which is great because it means publishers will not have to go back and redo all their EPUB2 files for EPUB3 specifications.

Since not all the cool features of EPUB3 are yet supported, BISG had created (and updates regularly) a grid that shows which devices support what. For example, only the iPad can do read aloud currently (Google also does read aloud, but not with media overlays), where text is highlighted while audio narration is being played. iPad also has the most EPUB3 features right now.


Amazon actually has two different formats: MOBI and KF8. MOBI was the first format Kindle used, and it’s kind of similar to EPUB2 but more limited. See Mobipocket for a list of what MOBI can do.

KF8 is Amazon’s newest format, and it is similar to EPUB3. Both KF8 and EPUB3 use HTML5 and CSS3, though KF8 is a little more limited. KF8 now displays on most Kindle devices (except I believe the first and second generation Kindles). KindleGen should convert EPUB to KF8, which is good news for self-publishers. According to Amazon’s site, KF8, in addition to HTML5 and CSS3 support, can do drop caps, fixed layout, text pop ups, and embedded fonts (all of which I have been able to do).

Learn more about specific KF8 features from my post, “The New Kindle Format (KF8).”

Other Tips

And that’s the gist of what you need to know! If you learn EPUB3 and KF8, you will be able to make any kind of e-book. Don’t know how to create an e-book? Take my Udemy course, How to Create Beautiful E-Books.


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