Ebook Formatting and Layout: ePub, Mobi, and PDF

Quick Answer: EPUB is the universal ebook format in 2026. Amazon KDP accepts EPUB uploads and converts them internally. MOBI is fully deprecated (Amazon stopped accepting MOBI files in March 2025). PDF works for print books but not for ebook distribution on major platforms. Format your ebook as a clean EPUB and it will work everywhere.

The format landscape for ebooks has simplified considerably. A few years ago, authors needed to produce multiple file types for different platforms. Today, EPUB handles nearly everything. Understanding the formats and their differences saves time and prevents upload errors.

EPUB: The Universal Standard

EPUB (Electronic Publication) is the open standard format used by Apple Books, Kobo, Google Play Books, Barnes & Noble, and essentially every non-Amazon ebook retailer. As of 2026, Amazon KDP also accepts EPUB files, which it converts to its proprietary Kindle format upon upload.

EPUB files are reflowable, meaning the text adjusts to fit whatever screen the reader is using. The reader controls font size, font choice, margins, and line spacing. This makes EPUB ideal for text-based content: fiction, non-fiction, memoirs, self-help, and business books.

EPUB comes in two versions. EPUB 2 is the older standard with wider compatibility across older devices. EPUB 3 supports more features (embedded fonts, audio, video, improved accessibility) and is the current standard. Most formatting tools export EPUB 3 by default, and all major platforms accept it.

When to use EPUB: For any ebook you plan to distribute through major platforms. It's the only format you need to produce for most projects.

MOBI: Deprecated

MOBI was Amazon's original Kindle format. Amazon stopped accepting MOBI uploads for reflowable ebooks in August 2021 and for fixed-layout ebooks in March 2025. The format is effectively dead for new publishing.

If you have older ebooks in MOBI format, they remain accessible to readers who already purchased them. But any new uploads or updates require EPUB, DOCX, or KPF format.

When to use MOBI: Never, for new publications. If you encounter guides or services that still reference MOBI as a required format, that information is outdated.

PDF: For Print, Not Ebook Distribution

PDF is a fixed-layout format: the content stays exactly where you put it, regardless of the device. This makes it excellent for print books (KDP Print, IngramSpark) and for ebooks with precise layout requirements (textbooks, graphic novels, design portfolios).

PDF is not accepted by Amazon KDP for ebook uploads. Apple Books, Kobo, and Google Play accept EPUB but not PDF for reflowable ebooks. PDF ebooks can be sold directly through your own website or platforms like Gumroad, Payhip, and Books.by, where you control the file format.

The practical limitation of PDF for ebook distribution is that the text doesn't reflow. On a phone screen, a PDF designed for a standard page looks tiny and requires constant zooming and scrolling. This makes it a poor reader experience for text-heavy books on mobile devices.

When to use PDF: For print book interiors, for direct-to-reader sales where layout precision matters (workbooks, design guides), and as a supplementary format alongside EPUB.

KPF: Amazon's Kindle Package Format

KPF files are created with Amazon's free Kindle Create tool. They're optimized for Kindle devices and produce reliable results on Amazon's platform. KPF is a solid choice if you publish exclusively on Amazon and want to use Amazon's own formatting tool.

The limitation is that KPF files are Amazon-only. They can't be uploaded to Apple Books, Kobo, or any other platform. If you distribute beyond Amazon, you'll need a separate EPUB for those platforms.

When to use KPF: If you're Amazon-exclusive and prefer using Kindle Create for formatting. Otherwise, EPUB covers Amazon and everywhere else.

Formatting Tools

Several tools produce clean EPUB files without requiring technical knowledge:

For most authors, Atticus (cross-platform, $147) or Vellum (Mac only, $249.99) produce professional results with minimal effort. Reedsy Book Editor is the strongest free option. Kindle Create is suitable for Amazon-exclusive authors who want a free tool.

What Good Ebook Formatting Looks Like vs What Does Not

Works well: - A clean EPUB that passes validation (epubcheck) and renders consistently across Kindle, Apple Books, Kobo, and phone screens. The table of contents is clickable, heading levels are consistent, and the cover image is embedded. - The author tests the formatted ebook on multiple devices (or at minimum, in Kindle Previewer and the Apple Books preview tool) before uploading.

Red flags: - The author uploads a DOCX file directly to KDP without testing, resulting in unexpected formatting issues (broken spacing, missing styles, misaligned images). DOCX uploads work, but conversion quality is inconsistent. - The ebook is formatted as a PDF and distributed through Kindle, resulting in tiny, unreadable text on phones and e-readers. - The author produces separate files for each platform without understanding that a single clean EPUB works everywhere.

The Takeaway

Produce one clean EPUB file. It works on Amazon (which converts it internally), Apple Books, Kobo, Google Play, and direct-sales platforms. Use a formatting tool like Atticus, Vellum, or the free Reedsy Book Editor. Test on multiple devices before uploading. The days of needing multiple file formats for different platforms are over. For the full formatting and conversion process, see the Ebook Formatting and Conversion guide.

Q: ePub vs Mobi vs PDF: Which format should you use? A: EPUB for ebook distribution on all platforms. PDF for print interiors and direct-sales workbooks. MOBI is deprecated and no longer accepted by Amazon. See ePub vs Mobi vs PDF: Which Format Should You Use? for a detailed comparison.

Q: Can you format an ebook in Microsoft Word? A: You can upload a DOCX file to Amazon KDP and it will convert, but the results are inconsistent. Formatting tools like Atticus and Vellum produce much more reliable output. See Can You Format an Ebook in Microsoft Word?

Q: What format does Amazon KDP accept? A: Amazon KDP accepts EPUB (recommended), DOCX, KPF, and HTML for ebook uploads. MOBI is no longer accepted as of March 2025. EPUB gives you the most control over the final result.