How to make an EPUB from a Word file, without uploading it

Drop the manuscript into BOOK: a Word file, a markdown file, plain text or a web page. The chapters are cut at the headings, each can be renamed, the title and author are set, a cover is chosen or drawn from the title, and Write the EPUB saves a file that Kobo, Apple Books, Google Play Books, calibre and every reading app open. A Kindle takes it through Send to Kindle. The file is written in the tab; nothing is uploaded, and it works with the network off.

What an EPUB actually is

An .epub is a zip. Inside it: one XHTML page per chapter, a stylesheet, the pictures, a package file that lists them and says what order they go in, and a table of contents. The first entry in the zip is a one-line file that says "this is an EPUB", stored uncompressed so a reader can check it before opening anything else. That is the entire format, and a browser can write every part of it: it already knows how to make a web page well-formed, and the pinned zip library on this site writes the archive.

The sites that "convert to EPUB" are doing this on a server. The price of that is an account, a queue, a watermark on the free tier, or a copy of your unpublished book on a machine you do not control. None of it is a necessary part of the job.

How the chapters are found

By the headings. If the manuscript has several Heading 1s, each one starts a chapter. If not, each Heading 2. Failing that, a horizontal rule; failing that, the whole thing is one chapter. Plain text without headings gets chapters wherever a line reads like one: Chapter Three, PART II, a short line in capitals. The page shows the list it found, with the word count of each, and the choice can be overridden: every Heading 1, every Heading 2, every rule, or no split at all. Chapter titles can be edited in the list before the book is written; the words are left alone.

A title on its own above the first chapter is taken as the book's title, not a three-word chapter. A Word file with one Heading 1 at the top names the book after it.

What comes across, and what does not

• Words, headings, bold, italic, lists, tables, links, block quotes and code come across as what they are.
• Pictures inside a Word file come across and are stored in the book as files. A picture that points at a web address is left out and counted, because a reader offline would show a broken box for it.
• A script, a form, a style block or an embedded frame is left out and counted. A book cannot hold them and a reader would refuse the file.
• Fonts, columns, page breaks and Word's layout do not come across. An EPUB reflows to the reader's screen and font size, which is the point of the format; the layout of the page is the reader's.

The cover and the details

A cover is optional; a book without one is valid and readers show the title. Choose a picture and it is resized and stored as a JPEG, or have one drawn from the title and author: a plain typographic cover in a colour picked from the title. The title, the author and the language go into the package file, which is what a reader's library shows and sorts by, so they are worth getting right before writing the file.

What is not there

This is the part a comparison page usually leaves out.

• Typesetting. One stylesheet, sensible margins, the reader's font. A book with a designed interior wants a design tool afterwards; this makes a clean, valid EPUB from words.
• Kindle's own formats. Amazon takes an EPUB through Send to Kindle and through its publishing desk; a .mobi or .azw3 is theirs to make.
• DRM. Deliberately. The file is yours and stays openable everywhere.
• Footnotes as pop-ups. A footnote in Word arrives as a numbered note at the end of the book, not as the pop-up some readers show.

Checking the file before you send it anywhere

Open it in READER on this site, or any reading app, and look at three things: the contents list has the chapters you expect with the names you gave them; the first chapter starts where the book starts, not with a stray title page of three words; and the pictures are there. PACK opens the zip itself if you want to see the parts. A build test on this site does exactly that check, on every change, against a book with a pasted picture, a web picture, a table and a script in it.

The short version