Ebook formats guide
Compare EPUB, MOBI, AZW3, and PDF ebook formats — understand which e-reader supports which format, and when to convert.
| Format | Creator | Supported by | Best for |
|---|---|---|---|
| EPUB | Idpf (open standard) | Kobo, Apple Books, Google Play Books, most non-Kindle readers | Universal ebooks, open web |
| MOBI | Amazon | All Kindle devices and apps | Kindle (older format) |
| AZW3 | Amazon | Kindle devices 2011+, Kindle app | Kindle (modern format, better formatting) |
| Adobe | Everything | Fixed-layout documents, printing |
EPUB is the open standard. It's supported by Kobo, Apple Books, Google Play Books, and virtually every e-reader except Kindle. If you want one format that works everywhere except Amazon's ecosystem, EPUB is the answer.
AZW3 (KF8) is Amazon's current Kindle format, replacing MOBI. It supports CSS styling, embedded fonts, tables, and complex layouts. If you have a Kindle released after 2011, AZW3 gives you the best formatting quality. Use the EPUB to AZW3 converter to load EPUB books onto your Kindle.
MOBI is Amazon's older Kindle format. It works on all Kindle devices including very old ones, but has limited formatting support. For modern Kindles, AZW3 is superior. MOBI remains useful for ensuring compatibility with the widest possible range of Kindle hardware.
PDF is not really an ebook format — it's a fixed-layout document format. PDFs look great on desktop screens and when printed, but are difficult to read on small e-reader screens because the text doesn't reflow. Avoid PDF for mobile or e-reader consumption unless you need the fixed layout (e.g., a heavily illustrated book or a textbook with complex diagrams).
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