Converting a manuscript to EPUB

Last updated August 2026

EPUB is the format every major ebook retailer except Amazon takes directly, and the one Amazon converts from most cleanly. If you are publishing anywhere beyond Kindle, you need one.

The conversion itself is easy. Getting a file that behaves properly on a phone, an e-ink reader and a tablet is where the work is, and almost all of the difficulty comes from decisions made in the manuscript long before anyone exports anything.

What an EPUB actually is

An EPUB is a ZIP archive containing a small website. Rename one to .zip, unpack it, and you will find XHTML files for the chapters, a stylesheet, your images, and two files that hold it together:

• a package document listing every file, the reading order, and the metadata — title, author, language, identifier
• a navigation document, which is the table of contents readers actually use

That structure explains the format's single most important property: an EPUB reflows. There are no pages. The reader chooses the font, the size, the margins and the theme, and the text rearranges to fit. Any effort you spend controlling where a line falls is effort spent fighting the format.

EPUB 3 is the current standard and what you should be producing. EPUB 2 still turns up in older tooling; there is no good reason to target it now.

Which route to use

The honest rule: the cleaner your source, the less the route matters. A well-structured manuscript converts acceptably through almost any of these. A manuscript held together with manual spacing converts badly through all of them.

Structure is what converts

A converter has no idea what your chapter headings are. It reads your document's structure and translates it. If the structure is a lie — a heading that is really 18pt bold body text — the EPUB inherits the lie.

Use real heading styles. Chapter titles must be Heading 1, not enlarged paragraph text. The navigation document is generated from headings, so text that merely looks like a heading produces an ebook with no working table of contents.

Use styles, not direct formatting. Selecting text and clicking bold is direct formatting. It survives conversion as inline markup that overrides the reader's own settings, which is exactly what you do not want.

Never fake spacing. Blank paragraphs to push a chapter down the page, tabs to indent, spaces to centre. All of it reflows into nonsense at a different font size.

Set the paragraph indent as a style property, not with tabs or spaces.

Mark scene breaks with a real element — a centred symbol in its own style — not an empty line. Whitespace at the foot of a screen is invisible, so readers cannot tell a scene break from a page ending.

The parts people forget

Metadata. Title, author, language and a unique identifier live inside the file. Language in particular affects hyphenation and how screen readers pronounce your book, and it is wrong in a surprising number of self-published EPUBs.

The cover. One portrait image, flagged as the cover in the package document rather than merely being the first page. Roughly 1600 × 2560 is a safe target. If it is not flagged properly, some readers show no thumbnail at all.

Front matter. Title page, copyright page, and — if you want it — a dedication. Keep it short. A reader sampling your book on a store page gets the first few percent, and spending it on front matter means the sample ends before the story starts.

Images. Size them for the largest screen they will realistically meet and no larger. A 4000-pixel-wide image in a novel is dead weight in the download and, on some retailers, a delivery fee you pay per copy.

Validate before you upload

EPUBCheck is the official validator. Retailers run it, or something like it, and a file that fails is rejected without much explanation. Running it yourself first turns a three-day rejection cycle into a two-minute fix.

Errors worth understanding rather than merely fixing:

• Broken internal links — a table of contents entry pointing at a file that isn't there, usually after a chapter was renamed or deleted
• Files not listed in the package document — an image that exists in the archive but is invisible to the reader
• Malformed XHTML — an unclosed tag, often from hand-editing
• A missing or empty language field

Then read it on a real device, or at least in more than one app. A file that validates can still be unreadable, and the fastest way to find that out is to open it.

Accessibility is now a requirement, not a courtesy

Ebooks sold into the European Union have had accessibility obligations under the European Accessibility Act since mid-2025, and retailers increasingly ask for accessibility metadata at upload. Most of what it asks for is what a well-structured EPUB already does.

• Real heading structure, in order, so a screen reader can navigate
• Alt text on any image that carries meaning — decorative ornaments do not need it
• Sufficient colour contrast if you set colours at all
• A declared language
• Accessibility metadata inside the file, describing what the book supports

Requirements evolve and vary by retailer and territory, so check the current rules for the stores you sell through rather than treating this list as complete. The direction of travel is clear enough to build for now.

What about Kindle?

Amazon does not sell EPUB — it converts what you upload into its own format. It accepts EPUB, and EPUB generally gives you more control than DOCX because you are handing over decisions already made rather than asking Amazon's converter to make them.

Check the result in Kindle Previewer before publishing. Conversion is where surprises appear, and Previewer shows you the file readers will actually get.

Exporting straight from your manuscript

The shortest path to a clean EPUB is not to convert one at all. If the tool you wrote in understands what a chapter is, the structure it exports is already correct — no styles to repair, no fake spacing to unpick, no headings that are only pretending.

Write Flow Studio exports EPUB directly from your manuscript, alongside PDF, DOCX and Final Draft .fdx. Chapters, scenes and front matter are structural in the app rather than formatting you applied by hand, so they come through as structure rather than as text that happens to look right.