EPUB vs PDF vs MOBI: Best Format for eBooks
The Key Difference: Reflowable vs Fixed
EPUB and MOBI are reflowable — the text adapts to your screen size, font preferences, and display settings. PDF is fixed-layout — every page looks exactly the same on every device. This fundamental difference drives every other trade-off between these formats.
EPUB: The Standard
EPUB is the open standard for eBooks, supported by Apple Books, Google Play Books, Kobo, Nook, and most other e-readers. It supports reflowable text, embedded fonts, images, and interactive elements. EPUB 3 supports audio and video. It's the most versatile eBook format and the one most publishers use. Every e-reader except Kindle supports EPUB natively.
MOBI/AZW: Kindle's World
MOBI was the original Kindle format, now largely replaced by Amazon's proprietary AZW/KFX formats. If you're writing for Kindle Direct Publishing, you'll work with these formats. Kindle also accepts EPUB now (since late 2022), automatically converting to their internal format. MOBI is essentially dead for new content — Amazon recommends EPUB for uploads.
PDF: When Layout Matters
PDF preserves exact layout: fonts, images, spacing, and positioning are identical everywhere. This makes PDF ideal for textbooks with complex layouts, technical documentation with diagrams, academic papers, comics/manga, and any content where visual layout is part of the content. The downside: PDFs are terrible on small screens — you're constantly zooming and scrolling.
Which Format to Choose
Publishing a novel or text-heavy book: EPUB. Reading on Kindle: EPUB or MOBI (Kindle converts EPUB now). Distributing a formatted report or textbook: PDF. Creating comics or image-heavy content: PDF or fixed-layout EPUB. Sharing documents for print: PDF. Maximum compatibility across all devices: offer both EPUB and PDF.