Kindle vs EPUB vs PDF — Which Format Do You Actually Need?

The Short Answer

For most authors: you need EPUB for everything except Amazon, and Amazon handles conversion automatically. If you're selling direct (your own website, Gumroad, Payhip), also offer a PDF. You almost certainly do not need to create a MOBI file anymore. Here's why — and what everything actually means.

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Why Ebook Formats Are Confusing

The ebook format landscape was genuinely chaotic for a decade. Amazon had its own proprietary formats. Adobe had theirs. Every device seemed to want something different. Authors were expected to deliver four different files and somehow keep them all consistent.

The good news: in 2025, things have simplified considerably. The industry has largely converged on EPUB 3 as the universal standard, and Amazon's own tools now accept EPUB and convert it automatically. You no longer need to manage MOBI files at all for most publishing workflows.

Here's what each format actually is and where it belongs.

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EPUB — The Universal Standard

What it is: EPUB (Electronic Publication) is an open standard maintained by the W3C and supported by virtually every ebook platform and reading device except Amazon's older hardware. EPUB 3 — the current version — supports reflowable text, multimedia, interactive elements, and complex layouts.

Where it works:

• Apple Books ✓
• Kobo ✓
• Google Play Books ✓
• Barnes & Noble (Nook) ✓
• Smashwords / Draft2Digital ✓
• Amazon KDP ✓ (KDP converts it to their format)
• Your own website ✓

What "reflowable" means: The text adapts to the reader's screen size and font preference. A reader on a Kobo with large text sees fewer words per page than someone on an iPad with small text — the EPUB adapts to both. This is a feature, not a bug.

When EPUB struggles: Complex layouts with fixed image positions, tables that span multiple columns, or highly designed interiors (cookbooks, textbooks, children's books) can behave unpredictably in reflowable EPUB. Fixed-layout EPUB exists for these cases but requires specialized formatting knowledge.

The bottom line: EPUB is the file format you should start with. Get this right and you can publish everywhere.

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Kindle Formats — AZW3, KFX, and the Death of MOBI

Amazon's Kindle ecosystem has used several proprietary formats over the years. Here's the current state:

MOBI: Amazon's older format. Still accepted by KDP but produces lower-quality output than uploading EPUB. Do not create MOBI files for new publications. Amazon's own documentation now recommends EPUB.

AZW3 / KF8: Amazon's intermediate format, generated during the KDP conversion process. You don't create this yourself — Amazon creates it from your EPUB upload.

KFX: Amazon's newest Kindle format, offering the best typography and layout rendering on modern Kindle devices. Again, Amazon generates this — you don't.

What this means for you: Upload an EPUB to KDP. Amazon handles all the Kindle-specific conversion. Done.

The only exception: if you want to preview exactly how your book will look on a specific Kindle device before publishing, download Amazon's free Kindle Previewer tool. It converts your EPUB and shows you a simulated device preview.

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PDF — For Direct Sales and Print

What it is: PDF (Portable Document Format) is a fixed-layout format. What you design is exactly what the reader sees, regardless of device or font settings. Unlike EPUB, a PDF does not reflow — the layout is locked.

Where it works best:

• Direct sales (Gumroad, Payhip, your own website) ✓
• Lead magnets and free downloads ✓
• Workbooks, planners, and fillable documents ✓
• Print-ready files for IngramSpark or KDP Print ✓

Where PDF struggles:

• Kindle and most dedicated e-readers — PDFs render poorly on small-screen devices because they can't reflow text. A PDF formatted for letter-size paper becomes unreadably small on a 6-inch Kindle screen.
• Apple Books and Kobo — technically accept PDFs but the reading experience is significantly worse than EPUB.

When you need PDF:

• You're selling direct from your website
• Your book is a workbook, planner, or visual guide where layout must be preserved
• You need a print-ready file
• You want to offer a "printable" version alongside your ebook

When you don't need PDF:

• You're publishing exclusively through Amazon KDP or other ebook platforms

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Fixed-Layout EPUB — The Special Case

For children's picture books, highly illustrated nonfiction, and cookbooks where page layout must be preserved exactly, there's Fixed-Layout EPUB (FXL). Unlike standard reflowable EPUB, FXL locks the design at specific dimensions — similar to a PDF but with ebook metadata and compatibility.

FXL is more complex to produce, requires specialized formatting, and doesn't work well on all devices. It's the right choice when:

• Your book has full-bleed illustrations
• Text is embedded in images
• Page layout is part of the reading experience (poetry collections, art books)

Most authors don't need FXL. If you're unsure, ask your formatter — they'll tell you quickly whether your book warrants it.

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Quick Reference: Which Format for Which Platform?

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Frequently Asked Questions

Do I need to hire someone to convert my book to EPUB?

Not necessarily — tools like Vellum, Atticus, and Reedsy's editor can produce clean EPUB files from a well-formatted Word document. However, if your book has complex layouts, images, or tables, professional formatting produces more reliable results across devices.

Can I convert a Word document directly to EPUB?

Yes, but proceed carefully. Word's built-in Save As EPUB feature produces inconsistent results. Better options: paste your manuscript into Reedsy Book Editor and export EPUB, or use Pandoc for a cleaner conversion. Always review the output on an actual device or in Calibre before publishing.

Is MOBI dead?

For all practical purposes, yes. Amazon stopped supporting MOBI downloads for Kindle devices in 2022. Upload EPUB to KDP. Don't create MOBI files.

Can I sell a PDF as an ebook?

Yes, and for direct sales it often works well — especially for visual books, workbooks, or lead magnets. Just be aware readers on Kindle devices will have a poor experience. Offering both EPUB and PDF covers your bases.

What's the difference between EPUB 2 and EPUB 3?

EPUB 3 is the current standard and supports better typography, multimedia, and layout features. Some older reading devices only support EPUB 2, but these are increasingly rare. Format for EPUB 3 and your book will work on 99%+ of modern devices.

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Final Thoughts

The ebook format question sounds technical, but the practical answer for most authors is simple: create a great EPUB, upload it everywhere, and add a PDF if you're selling direct. The era of managing five different file formats is largely behind us.

Where it gets complicated — complex layouts, children's books, highly illustrated nonfiction — is exactly where professional formatting earns its price. If you'd like help with your ebook's formatting and delivery, see what we offer →.