From a reflowable book to fixed pages
An EPUB has no pages. It is a zip of web documents that reflow to whatever screen is showing them, which is exactly why ebooks work on a phone and a seven-inch reader alike. What it does not do is print, or open on a machine without a reader app, or hold a fixed reference you can cite by page.
Converting to PDF trades the format's flexibility for those properties. Because the source has no page design of its own, the page size, typeface and margins you choose here are not overriding the publisher's layout — they are supplying one.
Reading the book in the right order
Inside the archive, chapters are separate XHTML files with names that mean nothing in particular. What gives them an order is the spine: a list in the book's package file naming each chapter in reading order. This converter finds the package file through META-INF/container.xml, reads the spine, and follows it.
That detail is the difference between a book and a shuffled pile of chapters — sorting zip entries alphabetically puts chapter 10 before chapter 2. Each chapter then begins on a fresh page, which is the one place a book's structure genuinely maps onto page breaks.
What comes across
Kept: chapter text, headings, paragraphs, lists, block quotes, italics and bold, embedded illustrations, and links.
Not kept:the cover, the navigation table of contents, the publisher's typography and stylesheets, footnotes, and page-list metadata.
The DRM question
Most books bought from major stores are encrypted and tied to an account. Their chapters cannot be read by anything but that store's reader, and no browser tool can change that — this one will tell you the chapters could not be read rather than producing an empty file.
Books that convert without trouble: anything from Project Gutenberg or Standard Ebooks, DRM-free purchases from publishers who sell that way, and EPUBs you made yourself.
Common uses
- Printing a book, or part of one, to read on paper
- Reading on a device that has no EPUB reader
- Getting a public-domain text into a fixed, citable form
- Sending a manuscript to someone as a normal document
Privacy
Everything runs on your device — the archive is unzipped in the tab and the PDF is written in memory. Nothing is uploaded.