Quick Summary
EPUB is the universal, reflowable ebook standard, and it is the file you upload to KDP and most other stores. MOBI is retired. KDP stopped accepting MOBI for reflowable ebooks in 2021 and ended fixed layout MOBI support in March 2025, so no new uploads use it. PDF keeps pages fixed, which makes it right for print interiors and review copies but wrong for a novel on a small screen. KDP also accepts DOCX, HTML, and KPF files from Kindle Create. Choose one master file format, validate it, and preview it before you publish.
Introduction
In the EPUB vs MOBI vs PDF question, EPUB is the format most authors need. Amazon KDP recommends it, Apple Books, Kobo, and Google Play Books use it, and it reflows to fit any screen. MOBI is Amazon’s retired legacy format, and KDP no longer accepts it for uploads. PDF is a fixed layout format that suits print interiors, review copies, and design heavy books, but it reads poorly as a standard ebook. Most authors need one clean EPUB for ebook stores and one print ready PDF for paperback.
This guide is for authors who are about to upload an ebook and feel confused by the alphabet soup of file types. Use it before you hire a formatter, buy formatting software, or follow an older tutorial that still tells you to create a MOBI file.
EPUB vs MOBI vs PDF at a Glance
Short answer: EPUB is the current standard, MOBI is retired, and PDF is for print and fixed layout uses.
| Format | Type | KDP Ebook Upload | Best For | 2026 Status |
| EPUB | Reflowable, or fixed layout | Yes, recommended | Every ebook store and direct sales | The standard |
| MOBI | Legacy reflowable | No | Nothing new, only old sideloaded files | Retired |
| Fixed pages, no reflow | Not suited to standard ebooks | Print interiors, review copies, design heavy books | Print and fixed use |
What Is EPUB
Short answer: EPUB is an open ebook standard where text adapts to any screen and font size, and almost every store and reading app supports it.
Apple Books, Kobo, and Google Play Books all use EPUB, and KDP now accepts it directly. When you upload an EPUB to KDP, Amazon converts it into its own internal Kindle format automatically. Guides name that internal format as KFX, and you never create it yourself. EPUB also supports accessibility features, which is one reason it is the format authors keep as their master file. If you sell your own ebooks directly, EPUB is also the format readers expect, as we explain in our guide to selling ebooks direct to readers.
What Is MOBI, and Why Is It Retired
Short answer: MOBI is Amazon’s old Kindle format, and KDP no longer accepts it for any new ebook upload.
Sources give slightly different dates, but they agree on the outcome. KDP stopped accepting MOBI for reflowable ebooks in 2021. One 2026 guide that cites KDP’s MOBI support FAQ says KDP ended MOBI support for fixed layout ebooks on March 18, 2025. Amazon also dropped MOBI from its Send to Kindle service in 2022. Old MOBI files can still exist in personal libraries, and some can be sideloaded onto older Kindle devices by USB. That does not make MOBI a current publishing choice.
Be careful with outdated advice. MOBI dominated older Kindle tutorials, so it still shows up in search results. If a vendor delivers a “MOBI for Amazon” package without explaining that KDP no longer accepts it, ask what workflow they actually use.
When Should You Use PDF
Short answer: Use PDF for print interiors, review copies, and design heavy layouts, not as your main ebook retail file.
A PDF keeps every page exactly as designed. That is perfect for print. KDP print and IngramSpark both need a print ready PDF. It is a poor fit for a standard ebook, because a PDF does not reflow, so readers on a phone must pinch and scroll. Layout heavy PDFs with columns, images, and tables also convert badly into reflowable formats. If you want maximum compatibility for readers who like PDFs, you can offer a PDF alongside your EPUB. Keep the EPUB as your retail file.
Which Format Does Each Platform Want
Short answer: Most ebook platforms want EPUB, and print platforms want a print ready PDF.
| Platform or Use | Format Needed |
| Amazon KDP ebook | EPUB recommended, DOCX, HTML, or KPF also accepted |
| KDP print and IngramSpark print | Print ready PDF |
| Apple Books | EPUB |
| Kobo | EPUB |
| Google Play Books | EPUB, and Google also accepts PDF |
| Direct sales from your own site | EPUB, ideally without DRM |
What About DOCX and KPF
KDP also accepts DOCX files from Word and KPF files from Kindle Create. A 2026 guide recommends choosing one master workflow. For maximum portability, use EPUB. If Kindle Create is your production tool, use KPF. Use a clean DOCX for a simple book. Then validate and preview that source, and stop maintaining legacy MOBI files. Professional formatting tools such as Vellum, Atticus, and Scrivener’s compile function produce EPUB by default.
How to Choose the Right Format
Follow these steps.
- List where you plan to publish. Kindle, Apple Books, Kobo, your own site, and print.
- Build one clean EPUB for every ebook channel. A single EPUB works across major retailers, and Amazon converts it on upload.
- Build a separate print ready PDF for paperback or hardcover. Treat it as its own file, as we explain in our guide to ebook formatting mistakes.
- Skip MOBI entirely for new uploads.
- Open the EPUB in the free Kindle Previewer and check phone and tablet views.
- Keep your master EPUB or source file safe, since it is the file you will reuse.
Common Mistakes With Ebook File Formats
The most common mistake is uploading a PDF as your ebook, which creates a fixed, hard to read experience. A second mistake is following an old MOBI tutorial. A third is building a separate file for every store when one EPUB would work. A fourth is converting a layout heavy PDF into EPUB and expecting a clean result. A fifth is skipping the preview step, since a file that uploads cleanly can still look broken on a device. Check your file before you publish, even when you use professional software.
Conclusion
The EPUB vs MOBI vs PDF choice is simpler in 2026 than the old tutorials suggest. EPUB is the format you build, keep, and upload to ebook stores. MOBI is retired, so skip it. PDF belongs to your print interior and any special fixed layout or review copy. Build one clean EPUB, one print ready PDF, preview both, and confirm current requirements in your KDP dashboard before you upload.
Frequently Asked Questions
What ebook format does KDP accept in 2026?
KDP accepts EPUB, which it recommends, plus DOCX, HTML, and KPF files from Kindle Create. It does not accept MOBI.
Does KDP still accept MOBI files?
No. Guides report that KDP stopped accepting MOBI for reflowable ebooks in 2021 and ended fixed layout MOBI support in March 2025. Use EPUB instead.
Can I upload a PDF as my ebook?
A PDF cannot reflow, so it gives readers a poor experience on small screens. Use EPUB for your ebook, and keep PDF for your print interior or review copies.
Do I need separate files for Kindle, Apple Books, and Kobo?
Generally no. One clean EPUB works across the major ebook retailers, and Amazon converts it into its own format on upload.
Which format should I use for a paperback?
Use a print ready PDF. Both KDP print and IngramSpark require one.
Can old MOBI files still be read?
Existing MOBI files can still work on some older Kindle devices through USB sideloading, but you should not create new ones for publishing.
A Note From Authors Publishing House
Choosing the right file formats is one small part of a clean launch. Our formatting team builds a validated EPUB for ebook stores and a print ready PDF for paperback, then checks both across devices before you publish. Visit authorspublishinghouse.com or reach out for a free consultation to talk through your files.
