Ebook file formats are confusing because authors hear old advice, new platform rules, and tool-specific recommendations at the same time.

The short version: EPUB is the main cross-platform ebook format. KPF is Amazon’s Kindle package format. MOBI is legacy.

EPUB is the best default archive file

EPUB is the open ebook format used across most major retailers and aggregators. A clean EPUB can be used for:

Apple Books.
Kobo.
Google Play Books.
Barnes & Noble Press.
Draft2Digital.
Many library and distribution workflows.

KDP also supports EPUB uploads, provided the file meets Kindle publishing requirements.

For most authors, the EPUB should be the file you preserve long term. If you later update the book, change links, add back matter, or upload to another retailer, the EPUB is usually the best starting point.

KPF is Amazon-specific

KPF stands for Kindle Package Format. It is commonly created through Amazon’s Kindle Create or Kindle Previewer workflow.

KPF can be useful when:

You are publishing only on Amazon.
You built the ebook in Kindle Create.
You want to preserve Kindle-specific layout behavior.
The book needs Amazon’s fixed-layout or enhanced workflow.

The tradeoff is portability. A KPF is not the file you upload to Apple Books, Kobo, Google Play, or Draft2Digital. If you rely only on KPF, you may need to rebuild the ebook when you expand outside Amazon.

MOBI is legacy

MOBI used to be a normal Kindle file format. That is why many older blog posts, service listings, and author checklists still mention it as if every ebook package needs one.

For new publishing workflows, MOBI should not be the default deliverable. It can still be useful for very old Kindle devices or private sideloading workflows, but it is not the modern standard for uploading a new ebook.

If someone promises “EPUB and MOBI” but does not mention current Kindle previewing or retailer acceptance, ask what they actually test.

Reflowable vs fixed layout matters more than the extension

The bigger decision is not only EPUB vs KPF. It is whether the ebook should be reflowable or fixed layout.

Reflowable ebooks are best for:

Novels.
Memoirs.
Business books.
Devotionals.
Most narrative nonfiction.

Readers can change font size, line spacing, device orientation, and screen size. The text reflows.

Fixed-layout ebooks are best for:

Children’s picture books.
Image-led books.
Some cookbooks.
Some textbooks or workbooks.
Books where each page must preserve a designed composition.

Fixed layout can look closer to print, but it is less flexible for readers. It also takes more care to build and test.

What a professional ebook file should include

A clean ebook is more than a conversion button.

Check for:

Clickable table of contents.
Logical heading structure.
Working internal links.
Working external links.
Clean paragraph spacing.
Proper first-line indentation where appropriate.
Images sized for screen reading.
Front matter and back matter that match the print edition.
Metadata that matches the publishing dashboard.
Testing in Kindle Previewer and at least one non-Kindle reader.

If the print book has page numbers, remember that a reflowable ebook does not behave like print. It needs a digital navigation structure, not just a copied print layout.

Whether you build the file yourself or hire it out, the checklist stays the same. We compare both paths in Atticus, Vellum, or a professional formatter.

What to upload by platform

Use this as a practical starting point:

KDP Kindle ebook: EPUB or KPF, depending on workflow.
Apple Books: EPUB.
Kobo: EPUB.
Google Play Books: EPUB.
Barnes & Noble Press: EPUB.
Draft2Digital: EPUB or a clean DOCX, but EPUB gives more control when professionally prepared.

Always check the retailer’s current help page before upload, because platform requirements can change.

Do not convert the print PDF directly unless it is simple

Print PDFs are built for fixed pages. Reflowable ebooks are built for screens. Many of the ebooks we are asked to repair began as a print PDF pushed through an automatic converter. A direct conversion can create:

Broken reading order.
Random line breaks.
Missing headings.
Bad hyphenation.
Images in the wrong place.
Footnotes that do not link correctly.
A table of contents that is visible but not functional.

If the source Word or InDesign file exists, use that. If only a PDF exists, budget real cleanup time, whoever does the work.

A sensible deliverable package

For most self-published authors, the useful ebook package is:

EPUB for broad retailer upload.
KPF if the Amazon workflow needs it.
PDF reading copy as a fallback proof.
Source file when possible.
A short note explaining what was tested.

Wellset Books’ eBook conversion package focuses on EPUB and Kindle-ready files with clickable navigation, working hyperlinks, and reader testing before delivery.

EPUB vs KPF vs MOBI in 2026: What Self-Publishers Should Upload