eBook Formats Guide: EPUB, PDF, MOBI, and Kindle

The world of ebook formats can be confusing, with different devices and apps supporting different formats. This guide helps you understand ebook formats and convert between them.

Major Ebook Formats

EPUB (.epub)

• Support: Most e-readers except Kindle
• Features: Reflowable text, DRM optional
• Used by: Kobo, Nook, Apple Books, Google Play
• Best for: General ebook distribution

MOBI (.mobi) / AZW (.azw)

• Support: Amazon Kindle devices
• Features: Kindle-specific features, DRM
• Used by: Amazon exclusively
• Best for: Kindle readers

PDF

• Support: Universal
• Features: Fixed layout, exact formatting
• Best for: Textbooks, comics, illustrated books
• Note: Doesn't reflow - poor on small screens

KFX (.kfx)

• Support: Modern Kindle devices/apps
• Features: Enhanced typography, smaller files
• Used by: Amazon's newest format

Format Comparison

*Kindle now supports EPUB as of late 2022

Converting Ebooks

EPUB to MOBI (for Kindle)

Use Calibre (free desktop software) or online converters. Simple conversion, usually works well.

PDF to EPUB

Challenging - PDF's fixed layout doesn't translate well to reflowable text. Results vary based on PDF complexity.

EPUB to PDF

Generally works well. Useful for printing or when fixed layout is preferred.

DRM Considerations

Many commercial ebooks have DRM (Digital Rights Management) that:

• Prevents copying to unauthorized devices
• Blocks format conversion
• Ties books to specific accounts

DRM-protected ebooks cannot be freely converted. You can only convert DRM-free ebooks.

Choosing the Right Format

• Kindle e-reader → MOBI/AZW3 (or EPUB now)
• Kobo e-reader → EPUB
• Apple Books → EPUB
• Any device/app → PDF (but won't reflow)
• Publishing → EPUB (most universal)

Tips for Ebook Management

• Use Calibre - Free library manager with conversion tools
• Buy DRM-free when possible - More flexibility
• Keep original format - Convert copies, not originals
• Test on target device - Verify conversion looks correct