EPUB to PDF

An EPUB to PDF converter takes an ebook and lays it out as fixed pages. EPUB is a reflowable format: the text has no pages of its own, and the reading app decides where lines and pages fall based on the screen and the font size you chose. PDF is the opposite, a format where every page is already drawn. Converting between them means choosing a page size and typesetting the book into it, which is why the result is a new layout rather than a copy of one.

Underneath, an EPUB is a ZIP archive of web pages. A file at a fixed location names the package file, the package lists every resource and the order the chapters are read in, and each chapter is XHTML. So the conversion is: unzip, read the reading order, pull the text and headings out of each chapter in that order, then typeset the result. All of that happens here in the browser, which is why the book never leaves your machine.

Be clear about what survives. Chapter order, headings, paragraphs and the text itself come through. The publisher's typography does not: fonts, exact line breaks, embedded images, footnote links and the table of contents as a clickable structure are dropped, because reproducing a reflowable book's styling as fixed pages faithfully is a typesetting job rather than a conversion. If you want the designed layout, the publisher's own PDF edition is the thing to look for. If you want the words, in order, on pages you can print or annotate, this is the right tool.

Two details in the pagination are worth the words. A heading that would otherwise land as the last line of a page is pushed to the next page, because a heading cut off from the text it introduces is the layout fault every reader notices. And the body size, margins and page size are yours to set, which matters more than it sounds: the same book at 11 point on A4 and at 14 point on A5 are very different objects, one for reading on a screen and one for printing.

Plain text is the other output, and it is the better one for some jobs. If you are searching the book, feeding it to a script, quoting from it or reading it in an editor, a .txt file with the chapters in order and no page furniture beats a PDF. It is also the fastest, since no layout work is needed.

One limit, stated plainly: this reads EPUB only. MOBI, AZW and AZW3 are Amazon's own formats and are not ZIP archives of web pages, so they cannot be opened in a browser. Calibre converts those to EPUB on your own machine, and the EPUB it produces works here. A file in one of those formats is named as such rather than failing with a confusing archive error.