File formats explained
EPUB vs KPF vs MOBI: which eBook format do you need?
A plain-English guide to eBook file formats, which stores accept which files, and why one well-built EPUB covers almost every self-publishing route.
By the Real Self Publishing formatting team · Updated 5 min read
Key takeaways
- EPUB is the open eBook standard used by Apple Books, Kobo, Google Play Books, and Barnes & Noble, and Amazon KDP accepts it too.
- KPF (Kindle Package Format) is created by Amazon's Kindle Create tools and can only be uploaded to KDP.
- MOBI is a legacy Kindle format that KDP no longer accepts for new reflowable eBooks.
- For most authors, one well-built EPUB 3 file is enough to publish on Amazon and every other major store.
eBook formats at a glance
| Format | Made by | Where you can upload it | Use it when |
|---|---|---|---|
| EPUB 3 | Open standard (W3C) | KDP, Apple Books, Kobo, Google Play, B&N, Draft2Digital | Almost always: one file for every store |
| KPF | Kindle Create / Kindle Kids' Book Creator | Amazon KDP only | You built the book in Amazon's tools |
| DOCX | Microsoft Word | KDP and most aggregators | Simple text books, if the styles are clean |
| MOBI | Legacy Kindle format | No longer accepted for new reflowable KDP books | Avoid for new books |
| AZW3 / KF8 | Amazon's device format | Not uploaded: KDP generates it | Never needed by authors |
EPUB: the universal eBook format
EPUB is an open standard, essentially a packaged website with HTML for text, CSS for styling, and a manifest describing the chapters. EPUB 3 supports accessibility features, embedded fonts, and fixed layout. Because Amazon KDP also accepts EPUB, a single clean EPUB lets you publish wide (on all stores) without maintaining separate files.
KPF: Amazon's Kindle Create format
KPF files come out of Amazon's free Kindle Create and Kindle Kids' Book Creator tools. They work well on KDP but can't be uploaded anywhere else, so if you also sell on Apple Books or Kobo you'll need an EPUB as well.
What happened to MOBI?
MOBI was the original Kindle format. KDP no longer accepts it for new or updated reflowable eBooks, and modern Kindles use Amazon's newer formats generated automatically from your upload. If someone offers you a 'MOBI file' as the main deliverable, ask for an EPUB instead.
Which format should you create?
- Publishing only on Amazon: EPUB or KPF both work, and EPUB keeps your options open.
- Publishing wide (Apple, Kobo, Google, B&N): EPUB 3.
- Picture book or cookbook: fixed-layout EPUB 3 for Apple and Kobo, plus a KDP-compatible fixed-layout build. See fixed-layout formatting.
- Also selling paperbacks: add a print-ready PDF for KDP Print or IngramSpark.
Every Real Self Publishing order includes Kindle-ready and EPUB files. See pricing or learn to format for Kindle yourself.
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Frequently asked questions
Can I upload an EPUB to Amazon KDP?
Yes. KDP accepts EPUB files for eBooks and converts them to Kindle format automatically. Check the result in Kindle Previewer before publishing.
Can I convert a KPF file to EPUB?
Not reliably. KPF is a proprietary Amazon format meant only for KDP upload. If you need to sell outside Amazon, build an EPUB from your source manuscript.
Is EPUB 2 still acceptable?
Most stores still accept EPUB 2, but EPUB 3 is the current standard and supports accessibility metadata and fixed layout. New books should use EPUB 3.