My EPUB export lost its chapter breaks

What an e-reader looks for

An ebook has no fixed pages. A reader app starts a new screen where the file tells it a new section begins, and it builds the table of contents from headings it can recognize as headings. Text that merely looks like a chapter title — bold, 18 point, centered — is ordinary paragraph text to the converter, and the chapter vanishes into the one before it.

Google Docs

1. Put the cursor in each chapter title and choose Heading 1 from the style box (Ctrl+Alt+1, or ⌘+Option+1 on a Mac). Use Heading 2 for anything below chapter level, never for chapters.
2. Open the outline with View › Show outline. Every chapter should be listed there; anything missing is not a heading yet.
3. Start every chapter after a page break (Insert › Break › Page break). Some reading apps honor it as a new screen.
4. Export again from File › Download › EPUB Publication (.epub).

Apple Pages

Pages works the same way underneath. Give every chapter title one paragraph style — a heading style from the template, or one of your own — and apply it consistently. Then choose File › Export To › EPUB and pick the reflowable layout, which is the one that behaves like a normal ebook. Pages builds the ebook's contents from its Table of Contents view, which lists paragraphs by style. If chapters are missing, open that view from the toolbar's View button, click Edit, and tick your chapter style. Leave it unindented at the top of the list, since that is the level Pages turns into chapter breaks.

Checking the result

Never judge an EPUB in one app alone. Open it in Kindle Previewer, which is free from Amazon and shows the navigation a Kindle will build, and in a second reader like Apple Books or Calibre's viewer. If you plan to upload anywhere that validates files, run it through EPUBCheck, the W3C's open-source validator, and fix what it reports. Structural errors there are often the same problem as the missing chapters.

In Tabularia

Chapters are a block style rather than a look, so a chapter exists as soon as a line is marked Chapter Heading, and the Outline lists it. The EPUB export writes each chapter as its own file in reading order with a navigation document, which is what gives a reader app its breaks and contents list. The exporting guide calls that EPUB a preview for e-readers. Validate it with the same tools before you sell it.