What Is the Difference Between EPUB and PDF?
Explains which format is right and when for first-time users.
Quick answer
You finished your book, export time has come — but which format? EPUB, PDF, or both? This question seems simple, but choosing the wrong format can lead to unnecessary technical issues, platform rejection notices, or visual glitches that ruin the reader experience.
Highlights
- • What is EPUB and how does it work?
- • What is PDF and when is it preferred?
- • Which format does KDP want?
Publishing note
Prepared and reviewed by the Book Generator editorial team.
The purpose is not to provide legal or professional advice, but to help you make clearer publishing decisions.
You finished your book, export time has come — but which format? EPUB, PDF, or both? This question seems simple, but choosing the wrong format can lead to unnecessary technical issues, platform rejection notices, or visual glitches that ruin the reader experience. Most users want both formats, rightfully so — but they don't know which one to start with or what the difference between the two really means. This article skips lengthy technical explanations and goes straight to the result: pick the right format, for the right purpose, at the right time.
What is EPUB and how does it work?
EPUB is an open standard developed for electronic publishing, and its name comes from 'electronic publication.' Its most fundamental feature is its reflowable structure: text automatically reshapes itself according to the reader's screen size, resolution, and font preference. When reading on a phone, lines narrow and adapt; on a tablet, they expand; on an e-reader, the user can increase or decrease font size — content remains readable under all conditions. This flexibility makes EPUB the standard for digital distribution. Amazon Kindle, Apple Books, Kobo, Google Play Books, and nearly all major e-book platforms support the EPUB 3 format. Amazon used to recommend the .mobi format; however, since 2022 it has adopted EPUB as its primary format. In short, if you plan to distribute digitally, upload to KDP, or send directly to the reader, EPUB should be your primary output.
What is PDF and when is it preferred?
PDF stands for 'Portable Document Format' and was developed by Adobe in the early 1990s. Its core feature is fixed layout: pages appear exactly as designed — font size, line spacing, image placement, and page margins never change. No matter which device or software opens it, the appearance remains the same. This makes it ideal for print: files sent to a printer, physical book production, full-page designed guides, or certificates all require PDF. If you want to publish a paperback or hardcover book on Amazon KDP, the interior text and cover must be prepared as separate PDF files. On the other hand, PDF is cumbersome for digital reading in many ways: reading on a phone screen is tiring, you constantly need to zoom in and out to fit lines, and font size cannot be adjusted by the user. That's why EPUB is preferred over PDF for uploading to e-book platforms.
Which format does KDP want?
Amazon KDP expects two different formats for two different publication types. Publishing a digital book (Kindle eBook) requires the EPUB 3 format, which KDP accepts directly. Before 2022, the .mobi format was also widely used, but Amazon now officially recommends EPUB and it is preferred for new uploads. KDP's own preview tool, Kindle Previewer, lets you upload your EPUB file and simulate how it will look on a Kindle screen — running this check before uploading is a good habit. For a printed book (paperback or hardcover), PDF is required. The interior text is one PDF, and the cover is a separate PDF. The cover PDF dimensions are determined by page count because spine thickness varies with page count. KDP provides a free cover template calculator to simplify this calculation. In summary: EPUB for digital, PDF for print — if you plan to do both, keep both formats ready.
Which should you get first?
The practical recommendation is clear: get EPUB first, leave PDF for later. When you get EPUB, you can easily check your book's structure, chapter ordering, heading hierarchy, and overall flow on an e-reader, Kindle Previewer, or browser-based tools. Which chapter heading appears at the wrong hierarchy level, does the table of contents show the correct links, is the flow logical — seeing all of this is much easier in EPUB. After catching and fixing structural issues here, generating the PDF saves time and prevents unnecessary revision loops in the PDF. If you're only doing digital distribution, you may not need PDF at all. If you're considering print, the order should be: verify content and structure with EPUB first, then check print layout with PDF. Getting both at the same time is also possible; however, for quality control logic, EPUB should always be the first step.
What to watch out for during conversion
The most critical point when producing EPUB is heading hierarchy. If H1 for book title, H2 for chapter headings, and H3 for sub-chapter headings are not marked correctly, the table of contents will be generated incorrectly and navigation will break in some reader apps. Check whether images are embedded inside the EPUB — linked images may not appear on some platforms. Also, testing your EPUB file with a validation tool like epubcheck before publishing prevents potential KDP rejection notices. When producing PDF, margins, font embedding, and page size are critically important. KDP offers general trim size options for printed books; the most common is 6x9 inches. Images with bleed areas require additional settings. Book Generator manages these technical details largely on your behalf and produces platform-compatible outputs; still, skipping the final quality check is not a good habit.
Summary: choose format by purpose
EPUB: digital reading, e-book platforms, Amazon Kindle, Apple Books, Kobo, mobile devices. Users can adjust font size, text adapts to screen size, and file size is small. PDF: print, fixed layout, printer file, KDP paperback interior and cover. Design is preserved with pixel perfection and appears the same across platforms. Both formats may be needed for different purposes, and one cannot replace the other. The starting point should always be EPUB: verify structure there, check content, and after approval move to PDF. Book Generator offers both formats as export options; getting both at the same time requires no extra effort.
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