Margins vs bleed — what's the difference?
Margins are the empty space between your text and the edge of the page. Bleed is the opposite idea — it is extra artwork that runs past the trim line and gets cut off, used only when something is meant to reach the very edge of the page. Most text-only books need margins but no bleed.
Inside (gutter) margin by page count
The inside margin — the gutter, next to the spine — must increase as your book gets thicker, because more pages curve more deeply into the binding. Use these minimums as a guide:
| Page count | Minimum inside (gutter) margin |
|---|---|
| 24–150 pages | 0.375″ |
| 151–300 pages | 0.5″ |
| 301–500 pages | 0.625″ |
| 501–700 pages | 0.75″ |
| 701–828 pages | 0.875″ |
Inside-margin minimums by page count. Going a little larger is safe; going smaller risks rejection.
This is the #1 margin mistake
Using a single fixed gutter for a 400-page book is the classic error. If text gets eaten by the spine, your gutter is too small for the page count.Outside, top and bottom margins
For the other three edges, keep at least 0.25″ of margin if your book has no bleed. If your interior does use bleed, allow at least 0.375″ so important content stays clear of the trimmed edge. Page numbers and running headers count as content — keep them inside the safe area too.
Setting up bleed correctly
When your interior has edge-to-edge images or colour, set bleed up like this:
- Enlarge your document page size by 0.125″ on the top, bottom and outside edges (not the spine edge).
- Extend any edge artwork all the way into that bleed area so there is no gap.
- Keep text and key elements inside the safe zone, well away from the trim line.
Official reference
Amazon documents exact bleed and margin figures per format in the KDP Help Center. Confirm the current numbers there before publishing.Related steps
- Make sure your text stays inside the live area — read the KDP safe zone guide.
- Lock your trim first — see KDP trim sizes.
- Verify everything before publishing with the upload checklist.
How KDPBuilder helps
KDPBuilder helps you prepare an interior PDF with the correct inside margin for your page count and safe outer margins for your trim size — and applies bleed when your layout needs it. The goal is simple: a print-ready file that meets Amazon KDP's formatting requirements so it is not bounced back at upload.