EPUB vs PDF: What’s the Difference and Which Does Your Ebook Need?

An EPUB and a PDF are two ways to package the same manuscript. An EPUB is reflowable: the text rearranges to fit any screen, which is what an ebook needs. A PDF is fixed: every page looks the same everywhere, which is why it is the preferred format for printing. For a normal text ebook, use an EPUB.

What’s the Difference Between an EPUB and a PDF?

The difference comes down to one idea: reflowable versus fixed. An EPUB (electronic publication) is built from the same web technology as a web page, so its text can “reflow” to fit whatever screen it lands on, and the reader can change the font, the text size, and the spacing. A PDF (Portable Document Format) locks every word and image to an exact spot on a fixed page, so the layout never moves.

It is also worth knowing there are two kinds of ebook. The first kind is the reflowable EPUB, and this format accounts for more than 99% of commercially available ebooks. The second is the fixed-layout ebook (a fixed-layout EPUB, or one of Amazon’s fixed-layout Kindle formats), where the page is locked like a PDF. Reflowable suits novels and most non-fiction; fixed-layout is for books whose design has to stay put, such as picture books, cookbooks, comics, and illustrated textbooks. We cover that choice in our guide to reflowable versus fixed-layout EPUB.

Which Format Do the Ebook Stores Want?

Most ebook stores are built around EPUB, but they split into two camps: those that will work with a PDF and those that will not. Even where a PDF is accepted, “accepted” is not the same as “best”:

• Amazon Kindle (KDP): recommends EPUB and also accepts Word (DOC/DOCX) and its own KPF (MOBI is no longer accepted). Among additional formats it accepts HTML, Rich Text, plain text, and Adobe PDF; PDF is only supported in certain languages (English, French, German, Italian, Portuguese, Spanish, Catalan, Galician, and Basque). Whatever you upload, KDP converts it to Kindle’s own format.
• Google Play Books: accepts both EPUB and PDF, but it distributes a PDF as a PDF (readers see “original pages”). Only if you also supply an EPUB do readers get a reflowable option, so a PDF-only book still reads poorly on a phone.
• Apple Books and Kobo: work from EPUB (Kobo also converts Word and ODT files to EPUB), and will not take a PDF as your sellable ebook.

So KDP and Google Play accept a PDF; Apple and Kobo do not. But KDP just converts it to reflowable text, and a PDF on Google Play reads poorly on a phone, so an EPUB is the safer choice everywhere.

If a PDF Is All You Have

Plenty of the books we convert begin life as a PDF, so it is a workable starting point. We just prefer an editable source first (a Word, Pages, or InDesign file), because there the words are still words, not shapes on a page, so the conversion stays clean. Extracting text from a finished PDF page is where faults creep in, so scan for these before you publish:

• Broken or run-together paragraphs. The extraction may split a paragraph at the end of every printed line instead of at the real paragraph break, or run separate paragraphs together with no break at all.
• Hyphens that should not be there. A soft hyphen added only to break a word at the end of a print line can become a permanent hard hyphen in the middle of your reflowed text.
• Missing characters from ligatures. Joined pairs such as “fi” and “fl” are a single typographic shape, not the separate letters, so they can drop out as blank spaces, turning “office” into “ofce”.
• Running heads and page numbers in the text. The chapter title or author name printed at the top of each page, and the folios (page numbers), can be pulled into the main text and interrupt the reading flow.

Our walkthrough of the most common PDF-to-EPUB conversion problems shows what to look for and how to fix each one.

Frequently Asked Questions

What is a fixed-layout ebook?

A fixed-layout ebook keeps the page design exactly in place, like a PDF, instead of letting the text reflow. The two main types are fixed-layout EPUB3 and Amazon’s Print Replica. They suit books where the layout carries meaning, such as children’s picture books, cookbooks, comics, and complex textbooks, and the tradeoff is that readers cannot resize the text.

Does Amazon have more than one fixed-layout format?

Yes. Amazon picks a Kindle fixed-layout format by book type: Print Replica preserves the exact print layout of textbooks and cookbooks (and does not run on e-ink Kindles); picture books and coffee-table books use Fixed Layout with Text Pop-Ups; comics use Image Pop-Ups, with Virtual Panels for manga; and large-type photo books use Fixed Layout without Pop-Ups. Amazon’s Comparing Formats chart lists them all.

Do I need separate files for print and ebook?

Usually yes. A printed book is produced from a fixed PDF and a reflowable ebook from an EPUB, and the two are separate outputs from the same manuscript. You generally cannot reuse the print PDF as your ebook and expect a good result on phones and e-readers.

What file should I give an ebook formatter or conversion service?

An editable source is best: a Word, Pages, or InDesign file. In those formats the words are still text, so the conversion stays accurate. A PDF can be used when it is all you have, but it usually needs extra cleanup because the text must be extracted from a fixed page.

Will a PDF work as a Kindle ebook?

It can. Amazon KDP accepts a PDF and converts it, and it can also turn a PDF into a fixed-layout Print Replica for illustrated books. For an ordinary reflowable Kindle book, though, an EPUB or Word file gives a cleaner result than a converted PDF.

Is an EPUB bigger or smaller than a PDF?

It depends on the book. For a plain novel the two are similar in size, and the EPUB can even be slightly larger because it also contains the cover image. For heavily illustrated books the EPUB is usually smaller, because its images are compressed to meet each store’s ebook file-size limit while the print PDF keeps the full-resolution images.