EPUB vs PDF: What Each Format Is Good For

If you have ever moved a digital book between devices, you have met this distinction whether you knew it or not. It is the one thing you need to understand to choose the version of a book you actually want.

PDF is a page

PDF, designed by Adobe in the 1990s, describes a printed page. It stores text and images positioned at fixed coordinates on a sheet of a particular size. When you zoom, you magnify a picture of a page. The layout will look identical on every device, which is exactly why publishers choose it for anything where the design matters — cookbooks, textbooks, children's picture books, anything with a diagram you must read the way it was drawn.

EPUB is a stream

EPUB is a reflowable format specified by the W3C. It stores text as text, in reading order, with instructions about how it should be presented. There is no fixed page. The reader's software decides the line length, the type size and the margins, and re-lays-out the text for whatever screen it is on. Change the font size on an EPUB and nothing is lost, because there was never a page to lose.

What that means in practice

• Screen size. An EPUB reads sensibly on a phone and on a desktop. A PDF read on a phone is a shrinking image of a page.
• Text size. EPUB text is resizable and stays sharp at any size. PDF text is fixed, and enlarging it often means the publisher's chosen font is no longer the font you are reading.
• Accessibility. EPUB carries structural markup — real headings, a reading order, alternative text for images — which is what screen readers need. A PDF carries none of that by default, which is why a poorly made PDF is effectively unreadable with assistive technology.
• Footnotes. EPUB can carry real footnotes that collapse and expand. In a PDF they are locked to the page where the publisher put them.
• File size. An EPUB is usually smaller for the same book, because it is not storing a page image.

Where PDF genuinely wins

Fixed layout is not a compromise, it is the point. A graphic novel, a cookbook, an atlas, a sheet music edition and most academic works depend on where things sit on the page. Reflowing those books would destroy them.

Which to get

For prose, get the EPUB. For anything visual, get the PDF. If a retailer offers both, the EPUB is the one that will feel native on whatever device you actually read on.