EPUB and print PDF are two different books
A print PDF and an EPUB are not two exports of the same thing. They are two different objects, and the difference is not cosmetic.
In a print PDF, you decide everything: the trim size, the margins, where each line ends, where each page breaks. Then it is frozen. The file that leaves your computer is the page that comes off the press.
In an EPUB, you decide almost none of that. The reader picks the typeface, the size, the line spacing, the margins, the screen — a phone in a dark room, a large-print setting on a tablet, a six-inch reader held sideways. The text re-wraps to fit. There are no pages in the sense you mean when you say the word.
What stops working when text reflows
Most ebook complaints trace back to one of these.
- Page numbers and cross-references. "See page 42" refers to nothing. Page 42 does not exist, or it exists differently for every reader. Cross-references in an ebook have to be links to a place in the text, or they have to be rewritten as "see the chapter on binding."
- An index of page numbers. The same problem, at scale.
- Images that sit exactly right. A figure you nudged until it balanced the page will float in a reflowed file. It lands wherever the text carries it, at whatever size the screen allows.
- Drop caps, running heads, and manual line breaks. Running heads do not exist — the device draws its own furniture. Drop caps survive only if built as styles, and behave differently across readers. Line breaks you typed by hand to fix print land mid-sentence on a narrow screen.
- Tables. A table that fits comfortably across a 6 × 9 page is often unreadable on a phone, where it either shrinks past legibility or scrolls sideways. Wide tables need rethinking for the ebook, not shrinking.
- A hand-set layout in general. The hours you spend leveling pages, fixing rivers and controlling widows are print work. They are real and worth doing, and none of them carry across. Converting a finished print layout into an ebook throws that work away and drags artifacts of it along.
In the Interior Formatter. One .docx manuscript produces both files — a print-ready PDF and an EPUB 3 — so the page-level print work and the reflowable ebook come from the same source instead of from each other. Start a book → · about the Interior Formatter
What an EPUB actually is
Open one up and it is not a document. It is a package: structured text with styles attached, a manifest listing what is inside, and a table of contents describing the order and hierarchy. It is much closer to a small website than to a word processor file.
That comparison explains what quality means here. A good EPUB is not one that looks a particular way on your device — you cannot control that, and the reader would override you anyway. A good EPUB is one that is correctly structured.
Structure is what makes one good
- Real headings. A chapter title has to be a heading, not a line of text you made bigger and centered. Headings are what build the navigation and what a screen reader announces.
- Real chapter breaks. Not a run of empty paragraphs pushing text down until it looks right. Empty paragraphs produce a gaping hole on one device and nothing at all on another.
- Styles, not manual formatting. Indent first lines with a style applied to the paragraph type, not with tabs or spaces.
- Text marked for what it is. A block quote marked as a quote. Meaning travels; appearance does not.
Do that and the file passes validation, reads well at any size, and works with assistive technology. Skip it and you get a mess.
Build both from one manuscript
The rule is simple: both outputs come from one clean manuscript. Neither one is made from the other.
Exporting an EPUB from your finished print PDF drags page-shaped decisions into a format with no pages. Rebuilding a print interior from an EPUB throws away every typographic decision print needs. Either direction, the two books drift apart, and the second one is visibly worse.
The Interior Formatter takes one .docx and produces both: the print-ready PDF and an EPUB 3 that carries accessibility metadata, proper chapter numbering, and an optional table of contents. Fix a typo in the manuscript, make both again, and they still agree. That is the point of the arrangement — not convenience, consistency.
Fixed-layout EPUB exists, and it is not for novels
There is a fixed-layout variety of EPUB where the page is frozen, like a print PDF. It exists for books whose layout is the content: picture books, comics, graphic novels.
It is the wrong choice for a novel or ordinary nonfiction. A fixed-layout file cannot reflow, so the reader loses the type size control they rely on, and on a phone it becomes a page they have to pinch and pan. If your book is words in a row, the reflowable format is the right one — and the cover is a separate file at a separate size, which Ebook cover size covers.
In the Interior Formatter. The EPUB it builds is structured for reflow from the start: accessibility metadata, numbered chapters, and an optional table of contents. Start a book → · about the Interior Formatter
Make yours
Everything here is built into the tools, and they are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: An EPUB that passes validation · More: Ebook cover size · How to format a book interior · Front matter, in order