PDF vs. EPUB: which is the best format?

We’ve received many questions recently about the differences between pdf format and epub format, so we thought it might be helpful to provide some details on the differences between the two formats.


PDF format was specifically designed not to be fluid, to the contrary; it’s meant to guarantee an identical display no matter what the support, without taking into account the size of the screen, etc. It’s the ideal format for preparing a document for printing on paper, since you can be sure that the layout you have prepared will display exactly the same for the printer as on your own computer. However, what makes it perfect for print is exactly what makes it unsuitable for ebooks, which must be readable in many different conditions, depending on the size of the screen and the needs and preferences of the reader.

To make pdf reading easier, on the Cybook Odyssey HD FrontLight, Bookeen proposes a reflow mode for pdfs, which simplifies the layout of your document to make it more readable on an ebook reader, which has a smaller screen than a PC or A4 format page.

PDF reflow mode

Even with this option, we recommend that you avoid the pdf format whenever possible, unless your document has been specifically formatted for your Cybook and your personal preferences (texte size, choice of font…) since the inherent rigidity of this format will never allow a completely personnalised display.


The EPUB format is specifically designed to provide an optimal reading experience on the support of your choice, by allowing the text to adapt to the size of the screen while still respecting the layout and formatting. EPUB allows you to modify the size of the text on the fly and to choose the font you prefer (did you know you can even add your favourite fonts to your Cybook? Just place the font files into the “Fonts” folder on your Cybook, then choose your favourite font from the menu while reading). Your Cybook even allows you to choose whether or not to activate justification, hyphenation, and even typographic ligatures if your font proposes them (for example Minion font, provided with your Cybook)!

Exemple de ligatures typographiques. Source : wikipedia.fr

Examples of typographic ligatures. Image from wikipedia.

EPUB is the ideal format for ebooks. For an optimal reading experience, we strongly recommend you choose EPUB whenever possible.

7 thoughts on “PDF vs. EPUB: which is the best format?

  1. There’s a bit more to it than simply “fitting many screen sizes. or being able to use ligatures. Typesetting and typography have evolved over thousands of years to satisfy two related but distinct requirements: The text must be eminently readable AND it must be “beautiful” in order to attract and guide the reader’s eye so the text is actually read.

    For very short documents, say a magazine article, the readability requirement is relaxed *a little* as one seldom develops eyestrain from reading magazine articles continuously for a long period of time. Still, “beauty” is required to attract the reader to stop and read the article, regardless of the content. Layout, typeface selection, color and contrast are crucial and sometimes the most critical factor, even if readability suffers a little.

    For a long text, say a novel, readability comes to the fore. Layout becomes a slave of readability. Ligatures, ornaments, paragraph indentation, line length &c. are useful in easing the reader’s navigation through a forest of letters which are best displayed with an even “color” and contrast. No, “color” in this context doesn’t refer to red vs. green vs. blue. It refers to the amount of “black” vs. “white” on the page. Imagine trying to read “Moby Dick” or “War and peace” when the type is set for Comic Sans Bold at 9 pt or Arial Narrow Light at 18 pt. Either on 90-character lines (or 20).

    Don’t get me wrong. EPUB is a great format for many textual needs, especially for portability. Sometimes, though, a well-set PDF is a whole bunch easier to read. To make a blanket statement that EPUB is the ‘optimal” or “ideal” format for books, though, ignores several thousand years of evolution and development in the art (yes, it is an art not so much a science) of making attractive, very readable books.


    1. Hello Bill,
      we couldn’t agree more about the importance of the art of typography. That’s why I made an exception, if you read the 3rd paragraph of the section about pdf, for pdfs which have been specifically formatted for your Cybook. However, I am more specifically referring here to larger or more complex pdf which has been “reflowed” mechanically to better fit a smaller screen than it was designed for, and this process will unavoidably degrade whatever typographic and stylistic qualities the original document has, while still not providing as optimal a result as a well-created and formatted epub.

      In addition, as I am sure you know, even a pdf created specifically for your Cybook would be unreadable on a smartphone with a smaller screen (I don’t read much on my smartphone, but when I’m standing in a long line at the market for instance I’m glad to be able to pass the time by reading a few pages of my book), and would not give an optimal result on a larger screen either. In addition, if the text size is too small for you to read comfortably, you cannot modify this without degrading the layout considerably and thereby losing the original advantages of the format. This is the strength of epub; it can adapt to different screen sizes, different needs of readers (larger text size or smaller for instance) while preserving the styles and layout of the original book.

      Certainly, this flexibility comes at a price, and it’s not possible (yet?) in epub to manage the typographical fine-tuning that is possible for a fixed format like print or pdf. But, the epub format is still young and evolving quickly; it is already possible to make a “beautiful” (speaking typographically) and highly readable ebook in epub, and over time the possibilities of the format and the reading systems will continue to improve. Epub book creators who understand the art of typography *and* the particular strengths (and constraints) of the format will continue to make the best ebooks, given that an essential characteristic of ebooks is accessibility and compatibility for everyone, regardless of their equipment.


  2. Hi.

    Will there be a search in the library? I have several hundred books on the reader and finding one by scrolling through a lot of pages is not an option.

    Please implement search!



  3. I am just beginning my education in e-printing, ePub, ebook, PD and the multitude of others that are in use today. I’m finding your material very helpful not just in what and how to d o something, but what NOT to do. Sometimes that’s as simportant as anything I can learn.

    Thanks for your helpful site.


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