Interior setup: margins, gutter and bleed
The gutter grows with your page count. Get it wrong and the inside edge of your text disappears into the spine.
A print interior fails in one of two ways: text vanishing into the spine, or text trimmed off at the edge. Both are avoidable with numbers you can look up in a minute.
The gutter grows with the book
The gutter is the inside margin, next to the spine. A thick book does not open flat, so a thick book needs a wider gutter. KDP sets minimums by page count:
| Page count | Minimum gutter |
|---|---|
| 24–150 | 0.375 in |
| 151–300 | 0.5 in |
| 301–500 | 0.625 in |
| 501–700 | 0.75 in |
| 701+ | 0.875 in |
These are minimums, not targets. Add 0.125 in if your book is text-heavy — readers should not have to crack the spine to finish a line.
Note the trap: page count is not final until the interior is finished, and the interior depends on the gutter. Lay out with your best estimate, check the final count, and if it crossed a threshold, widen the gutter and re-flow.
Outside margins
The other three edges need at least 0.25 in without bleed, or 0.375 in if the book uses bleed. Again, minimums. Anything under about 0.5 in looks cramped in the hand even when it passes review.
Bleed is for ink that runs off the page
If any element — a photo, a background block, a page-edge rule — is meant to reach the paper's edge, it has to be printed oversized and cut through. That overlap is bleed, and KDP wants 0.125 in on the top, bottom and outside edges. Never on the gutter edge.
Set your document to trim size plus 0.125 in on those three sides, push the artwork out into that zone, and accept that everything in it will be sliced off. Anything you need to survive should sit at least 0.25 in inside the trim line.
Most novels use no bleed at all. If your interior is text on white, skip it — it only adds ways to get cut.
Export settings that pass review
- PDF, with all fonts embedded. Not a Word file.
- Images at 300 DPI at their printed size. A 300 DPI image scaled up to double size is a 150 DPI image.
- Black text as pure black, not a rich-black mix, or small type prints fuzzy.
Before the next lesson
Export the interior and note the exact final page count. The cover cannot be built without it — that number sets the spine width, and a spine off by a millimetre puts your title on the front of the book.