How to Format a Book for KDP
KDP has specific formatting requirements for print and Kindle files. Getting them right the first time saves rejection emails and rework. Here is what KDP actually wants.
What KDP actually wants
KDP accepts two main file types: print PDF for paperback and hardcover, and EPUB for Kindle. Each has specific requirements. Getting them wrong means KDP rejects your file, and you have to fix and resubmit.
For print PDF, KDP wants: embedded fonts, no crop marks, correct trim size, gutter margins that scale with page count, and a single-page PDF. For EPUB, KDP wants: a reflowable file (not fixed-layout), semantic HTML, and reader-controlled body text.
Choose your trim size
KDP offers five standard trim sizes for paperbacks: 5x8, 5.25x8, 5.5x8.5, 6x9, and 7x10 inches. Each has a default body size that works well for that page dimensions. 5x8 typically uses 10.75 point body text. 6x9 uses 11 point. 7x10 uses 10.5 point.
Your trim size affects everything: the body font size, the type scale, the gutter margins, and the cover dimensions. Choose it early and build your typography around it.
Gutter margins that scale with page count
Gutter margins are the inner margins on a printed book page. They need to scale with your page count because more pages means a thicker spine, which means more text disappears into the binding. KDP provides a table that maps page count to minimum gutter width.
Calculating gutter margins by hand is error-prone. A good formatting system computes them automatically based on your actual page count, measured in a two-pass render. The first pass counts pages, the second pass applies the correct margins.
Embed your fonts
KDP requires that all fonts be embedded in your print PDF. If you use a font that is not embedded, KDP may reject the file or substitute a different font, which can break your typography.
Open-license fonts can be bundled and embedded freely. Commercial fonts may have licensing restrictions on embedding. Always check the font license before embedding. If you use a commercial font that cannot be embedded, you may need to substitute an open-license alternative.
Run a readiness check before export
Before you export, run a readiness check. This should report: missing chapters, placeholder text, unresolved severe conflicts, unsupported claims, duplicate titles, and missing front matter. Every warning should link you to exactly where to fix it.
You may override warnings, but they should stay on the export record. This way, if KDP rejects the file, you can check what warnings you overrode and see if any of them were the cause.