KDP Trim Sizes Explained: Which to Pick and Why (2026)
Updated August 4, 2026 · by the AI Books Writer typesetting team
KDP trim sizes and when to use each
| Trim size | Best for | Feel |
|---|---|---|
| 5×8″ | Novellas, poetry, short fiction | Compact paperback |
| 5.25×8″ | Fiction, thrillers | Mass-market feel |
| 5.5×8.5″ | Fiction, memoir, self-help | Trade paperback |
| 6×9″ | Novels, non-fiction, business — the default | Standard trade |
| 7×10″ | Textbooks, manuals, cookbooks | Large format |
| 8×10″ | Children's books, photo-heavy books | Picture-book |
| 8.5×11″ | Workbooks, planners, puzzle books | Letter size |
Bleed, margins, and the gutter
If your interior art runs to the page edge, add bleed: 0.125″ to the outside edges (final PDF = trim width + 0.125″, height + 0.25″). Text-only books don't need bleed.
The gutter (inside margin) must grow with page count, or text drowns in the binding. KDP's minimums:
| Page count | Minimum inside margin |
|---|---|
| 24–150 | 0.375″ |
| 151–300 | 0.5″ |
| 301–500 | 0.625″ |
| 501–700 | 0.75″ |
| 701–828 | 0.875″ |
Choosing a smaller trim raises the page count (same words, smaller pages), which raises the printing cost and can push you into a bigger required gutter. Trim size is a pricing decision disguised as a design decision.
Frequently asked questions
What is the most popular KDP trim size?
6×9 inches — the standard for novels and non-fiction, and the size most printers, reviewers, and readers expect for a trade paperback.
Do I need bleed on my KDP book?
Only if images or backgrounds run to the page edge. With bleed, your PDF must be trim width + 0.125″ wide and height + 0.25″ tall. Text-only interiors need no bleed.
Can I change trim size after publishing?
Yes, but a new trim changes the page count, which changes the spine width and printing cost — the cover must be rebuilt and the book re-reviewed.
Skip the formatting entirely
AI Books Writer turns an idea into a complete KDP-ready book — manuscript, print PDF at exact trim size with the correct spine and gutter, EPUB, and an AI-designed cover. The first book is free.
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