One file cannot be both. It has to be two.

An author uploads their beautifully formatted print PDF as their ebook, and the reviews arrive within a week: the text is tiny, it will not resize, and readers on phones give up entirely. The file was not broken. It was the wrong kind of file.

This is the most expensive misunderstanding in self-publishing, and it comes down to one distinction that is worth getting properly clear.

Reflowable versus fixed

An EPUB is reflowable. It contains your text and a description of what each element is, and the reader's device decides how to display it. The reader chooses the typeface, the size, the margins, the line spacing, and the background colour. There are no pages in any fixed sense, because the same book produces a different number of screens on every device.

A print PDF is fixed. Every page is an exact size, every element sits at exact coordinates, and nothing moves. The page count is a definite number, which matters because it determines your spine width and your printing cost.

These are opposite design philosophies. One surrenders control to the reader by design, and the other holds every position precisely. A file built for one cannot behave like the other, which is why the conversion people hope for does not exist.

What goes wrong in each direction

Both substitutions fail, and they fail differently.

Print PDF used as an ebook. The reader cannot change the text size, which for anyone with imperfect eyesight makes the book unusable. On a phone, a page sized for paper becomes unreadably small, and pinch-zooming through a novel is not a reading experience anyone tolerates. Reviews mention it specifically, and those reviews sit on the product page permanently.

EPUB sent to a printer. This simply does not work. There is nothing to print, because the file contains no fixed pages. It will be rejected at upload rather than producing a bad book.

The asymmetry matters: the first mistake produces a bad product that ships, and the second produces an error message. The dangerous one is the mistake that succeeds.

There is a third variant worth naming, because it is the most seductive. Some authors build one file that is neither properly reflowable nor properly fixed: a print PDF with generous type, or an EPUB with hard-coded font sizes intended to preserve a particular look. The reasoning is that a compromise should work acceptably in both places. In practice it works poorly in both, because each format's strengths come precisely from committing to its own model. A fixed file that gives up control has lost the reason to be fixed, and a reflowable file that overrides the reader has lost the reason to reflow.

What a good EPUB contains

Since the reader controls presentation, an EPUB's quality lies in structure rather than appearance.

Most of these are invisible when the file works and obvious when it does not. A reader never notices good structure. They notice a table of contents that lands two chapters off.

What a good print PDF contains

Print is the opposite discipline: everything is fixed, so everything must be deliberate.

• Correct trim size, matching what you selected at upload, with bleed only if images run to the edge
• Mirrored margins, with the inner margin wider to allow for the binding, which is the detail that most obviously separates professional interiors from home-made ones
• Running heads and page numbers that behave correctly, meaning no page number on a blank page and no running head on a chapter opening
• Controlled chapter openings, usually on a right-hand page, with blanks inserted to force it
• No orphans or widows, meaning no single line stranded at the top or bottom of a page
• Embedded fonts, or the printer substitutes its own
• An even final page count, since books print in signatures

The other formats you may hear about

EPUB and print PDF cover almost every case, and a few other names come up often enough to be worth placing.

• MOBI and AZW. Amazon's older formats. MOBI is retired and no longer accepted for upload, so anyone still asking for one is working from outdated instructions.
• KPF. What Amazon's own tool produces. Fine if you publish only to Amazon, and it locks you into their ecosystem because nobody else accepts it.
• Fixed-layout EPUB. A genuine exception to the reflowable rule, used for children's picture books, cookbooks, and graphic novels where the relationship between text and image is the content. It behaves more like a PDF and is a specialist job.
• Web PDF. A screen-oriented PDF, occasionally used for direct sales from your own site. Not a substitute for either an EPUB or a print file.
• DOCX. Your manuscript, not a book format. Some platforms accept it and convert it, and the conversion is exactly as good as you would expect.

The practical takeaway is that the list of formats you actually need is short. A reflowable EPUB and a print PDF cover standard fiction and nonfiction completely, and everything else on that list is either legacy, platform-specific, or a specialist case.

Why a converted document is not a formatted book

Every word processor offers to export an EPUB, and the result usually opens without error. That is why so many authors believe formatting is a solved problem they can handle in an afternoon.

What the export produces is a technically valid file carrying every structural habit of the source document. Chapter headings that were made large and bold by hand rather than styled as headings generate no navigation. Paragraph indents created with tabs collapse or double when the text reflows. Empty paragraphs used to push a chapter down the page create stranded blank screens on a phone. Direct formatting produces bloated markup that renders unpredictably across devices.

None of that stops the file opening, which is the problem. It opens, it looks acceptable on the machine that made it, and it degrades on hardware the author never tested. The reader who bought it on a phone sees something different from what the author approved on a laptop, and the review reflects their experience rather than yours.

Which do you actually need?

That depends on where you intend to sell, and the honest answer for most authors is both.

Ebook only is a reasonable starting point if you are testing a market, publishing something short, or want the lowest cost to launch. The limitation is not the missing revenue so much as the missing page count, because your cover spine cannot be finalized until a print interior exists.

Print matters more than its share of sales suggests. It is what people buy at events, what they give as gifts, what libraries and bookshops can stock, and what makes the book feel real to its author. Many books sell modestly in print and benefit disproportionately from existing in it.

That combination is why the middle tier at $690 covers both, and why it is what most authors publishing a standard novel or nonfiction book end up needing. The full formatting guide sets out what each tier includes.

Where formatting sits in the sequence

Formatting comes after editing and before the cover is finalized. That order is not preference, it is dependency: pagination depends on final wording, and the spine depends on pagination.

Authors who format before editing pay to paginate text that then changes, and authors who finalize a cover before formatting rebuild the spine. Neither is a disaster and both are avoidable by deciding the order once at the start.

Our formatting service delivers files built to upload to Kindle, Apple Books, Barnes & Noble, Google Books, and IngramSpark, in 7 days from receipt of a final manuscript. See what your tier costs before committing to anything. Barker Publishing House has been formatting books since 2018, and you keep 100 percent of your rights and royalties.