Converting EPUB to PDF: Why It Is Harder Than It Should Be

EPUB is the open standard for ebooks. PDF is the universal document format. Converting between them should be trivial since both contain styled text and images. But the fundamental difference in how they handle layout makes this conversion surprisingly complex. The fundamental mismatch EPUB is a reflowable format. The text adapts to the screen size, like a web page. There are no "pages" in an EPUB -- the content flows continuously and the reader application decides where page breaks fall based on the display size. PDF is a fixed-layout format. Every character has an exact position on a specific page. The layout does not change regardless of the display size. A PDF designed for A4 paper always looks like A4 paper, whether you view it on a phone or a projector. Converting from reflowable to fixed layout means you must decide: what page size? What margins? What font size? Where do page breaks fall? These decisions do not exist in the EPUB because they are left to the reader. The conversio