How to create an EPUB

What an EPUB actually is

An EPUB is a zip file with a specific structure inside it: one or more XHTML documents holding your text, a stylesheet, your images, a navigation document describing the table of contents, and a manifest listing the lot.

That is worth knowing even if you never open one, because it explains the single most important property of the format. Your text is marked up as structure — this is a heading, this is a paragraph, this is a block quote — and the reading app decides how that structure looks. You do not control the appearance. You control the meaning.

Reflowable

Text rewraps to the reader's screen, type size and margins. There are no pages, and page numbers are meaningless.

EPUB 3

The current version. Supports better accessibility metadata, mathematics, and media overlays. Use it; EPUB 2 is legacy.

Fixed-layout EPUB

A variant where pages ARE fixed. Correct for children's picture books, comics and cookbooks; wrong for anything text-led.

What changes from print

Getting the structure right

Almost every EPUB problem is a structure problem. The checklist:

• Real headings, in order, without skipping levels. h1 for the book or chapter, h2 beneath it, h3 beneath that.
• One XHTML document per chapter. A single-file EPUB is technically valid and painful to read on older devices.
• A navigation document generated from those headings — never typed, because a typed one goes stale the moment you rename a chapter.
• A declared language on the root element. Absent is not neutral: it makes a screen reader guess, and it usually guesses English.
• Alt text on every image that carries meaning, and empty alt on every image that is decoration.
• Semantic markup for the parts a reader navigates by — the epigraph is a blockquote, the scene break is an hr or a styled div, not a paragraph of asterisks.

Front matter in an ebook

Shorter than print, and in a different order, because a reader on a store's sample sees the first 10% of the file and you do not want that to be four blank pages and a dedication.

• No half title, no blank versos — both are print-only conventions.
• Title page, copyright page, then straight into the book. Dedication and epigraph if you have them, kept brief.
• The table of contents is the navigation document. A visible contents page as well is optional and often skipped in fiction.
• Move the acknowledgements to the back. In an ebook they are between the reader and the story.

Retailer differences

One EPUB is accepted everywhere, but the platforms are not identical and a few differences are worth knowing:

Amazon KDP

Converts your EPUB to its own format on upload. Check the result in Kindle Previewer, not in a generic EPUB reader — the conversion changes things.

Apple Books

The strictest validator of the major stores, and the most faithful to your CSS. If it passes here it passes everywhere.

Kobo

Accepts EPUB directly and renders it fairly literally.

Draft2Digital

Distributes one EPUB to many stores. Build to the generic profile rather than to any one retailer's quirks.

Validating and testing

1. Run EPUBCheck. It is free, it is what the retailers run, and a failure is a rejection.
2. Open the file in Kindle Previewer and in Apple Books. Read a chapter in each.
3. Change the type size twice in each app. Anything that is going to break will break here.
4. Turn on a screen reader and listen to the first page. It is uncomfortable the first time and it finds things nothing else does.
5. Check the navigation document actually jumps to the right chapters.