Almost every formatting disaster on Kindle comes from the same misunderstanding: authors format a manuscript the way they would format a printed page. They centre the chapter title, press Enter eight times to push text down, indent with the space bar, and pick a font they like. On paper all of that works. On a Kindle, where the reader controls the font, the size, the margins, and the orientation, all of it falls apart — and the result is the book that looks fine on your laptop and broken on someone's phone.
Formatting for ebooks is not about controlling appearance. It is about describing structure and letting the device handle appearance.
Reflowable vs Fixed Layout: Pick the Right One First
| Reflowable | Fixed layout | |
|---|---|---|
| Text behaviour | Reflows to fit any screen and font size | Page stays exactly as designed |
| Right for | Novels, non-fiction, memoir, most books | Picture books, comics, highly designed cookbooks |
| Reader control | Font, size, margins, dark mode | Almost none; readers zoom and pan |
| Accessibility | Good; works with text-to-speech | Poor |
If your book is mostly words, it is reflowable, and everything below applies. Choosing fixed layout because it looks tidier in the preview is a mistake you will hear about in reviews from readers on small phones.
Structure Is the Whole Job
Use real heading styles
Chapter titles must be actual Heading 1 (and sub-sections Heading 2), applied with your word processor's styles — not body text made large and bold. This is not cosmetic pedantry. The heading structure is what generates the navigable table of contents that the Kindle's menu uses, and it is the difference between a reader being able to jump between chapters and being stuck scrolling.
Start chapters with a page break, not with Enter
Repeated empty paragraphs to push a chapter onto a new page produce large random gaps once the text reflows at a different font size. Insert a genuine page break (in Word, Ctrl+Enter) and delete the blank paragraphs.
Indent with paragraph settings, not spaces or tabs
Set a first-line indent of roughly 0.2–0.3 inches in the paragraph style. Spaces and tabs survive conversion unpredictably and produce ragged openings. Also pick one convention and hold it: either indented paragraphs with no space between them (fiction), or block paragraphs with space between and no indent (much non-fiction). Doing both is the most common amateur tell.
Include two kinds of contents, or one, deliberately
There is the logical table of contents, built from your headings and reached through the Kindle's own menu, and there is an optional in-body contents page with links, which readers see as the first page. Reflowable ebooks should not include page numbers in either — there are no fixed pages. For a novel, a logical TOC alone is usually enough; for reference non-fiction, include both.
Details That Quietly Break Things
- Do not embed body fonts in a reflowable ebook. The reader chose their font for a reason, often an accessibility one. Reserve any font choice for headings if at all.
- Avoid text inside images. It cannot be resized, searched, or read aloud, and it turns to mush on a small screen.
- Size images sensibly. Around 1,000–2,000 pixels on the long edge is ample for most interior images; larger files inflate your delivery fee on the 70% royalty plan without looking any better. Our pricing guide explains how that fee works.
- Straight quotes and double spaces after sentences are the two marks that make a book look self-published. Run a find-and-replace for both.
- Hyperlinks should be real links with descriptive text, not bare URLs printed in the body.
- Copyright page, yes; page numbers, no. Front matter in an ebook should be short — a title page and a copyright page. Readers get a sample, and a five-page preamble spends it on nothing.
Japanese and other vertical scripts: if you are publishing in Japanese, vertical typesetting (tategaki) is not a font setting — it changes the writing direction, the page progression (right to left), and how numbers and Latin words are handled inside the text. A file typeset horizontally and flipped will look wrong to every Japanese reader. Make sure whatever produces your file supports vertical layout natively; we wrote about that separately.
Paperback Formatting Is a Different Discipline
Everything above assumes a screen. Print reverses most of it: the page is fixed, you supply a print-ready PDF, and you must embed your fonts.
- Trim size first. 6×9 inches is the default for most trade non-fiction and fiction in the US market; choose it before you lay out anything, because changing it later re-flows the entire book.
- Mind the gutter. Inside margins must be wider than outside ones so text does not disappear into the spine, and the requirement grows with page count. KDP publishes minimum margins by page count — use them as minimums, not targets.
- Bleed only if you mean it. If any element runs to the edge of the page, the whole interior must be set up with bleed. If nothing does, do not enable it.
- Embed every font in the PDF. Unembedded fonts are one of the most common print rejections.
- The cover is a separate file sized to your final page count, because page count determines spine width. Design the cover last.
Check It Before You Publish
Upload your file and open KDP's previewer, then actually use it: switch between a phone, a tablet, and an e-ink device; change the font size to the largest setting; turn on dark mode. Most layout bugs only appear at extremes. Then check the navigation menu to confirm every chapter is listed and every entry jumps to the right place.
Things worth a deliberate look: the first page of each chapter, any table or list, every image, the copyright page, and the very end of the book. If you have an EPUB, running it through an EPUB validator before upload catches structural errors that the previewer renders around.
If You Would Rather Not Do This by Hand
All of the above is learnable in an afternoon and tedious forever after. If you already have a manuscript — a Word file, a pile of blog posts, notes — our manuscript formatter takes your text and produces properly structured EPUB, PDF, and DOCX files with a real heading hierarchy and navigable contents, including vertical Japanese if you need it. And if the book does not exist yet, the free sample generator will show you the structure it produces from nothing more than a title.
Either way, the standard to hold yourself to is simple: open the finished file on the smallest phone you own, set the font one size larger than you find comfortable, and read the first chapter. If that looks right, the formatting is right.