Note · 2026-09-21
What margins does a KDP paperback need? Gutter, outside, top and bottom, by page count
Amazon KDP sets a minimum inside (gutter) margin that grows with your book's page count, plus fixed outside, top and bottom minimums. Here is the exact table and what happens if you get it wrong.
Amazon KDP requires a bigger inside margin (the gutter, next to the spine) as a paperback gets thicker, because more pages means more of the inside margin disappears into the binding curve. The minimum is not one number for the whole book: it is a lookup by total page count. For a standard 6×9 or similar trim, KDP's published minimums are 0.375 in up to 150 pages, 0.5 in up to 300 pages, 0.625 in up to 500 pages, 0.75 in up to 700 pages, and 0.875 in up to KDP's page ceiling of 828 pages. Outside, top and bottom margins do not scale with page count — KDP's floor for those is 0.25 in, though most professionally typeset interiors use more for readability. Get the gutter wrong and KDP either rejects the file at review or, worse, approves it and prints a book where the first two or three characters of every line disappear into the spine.
The full gutter table
| Pages | Minimum inside (gutter) margin | |---|---| | up to 150 | 0.375 in | | 151–300 | 0.5 in | | 301–500 | 0.625 in | | 501–700 | 0.75 in | | 701–828 | 0.875 in | | over 828 | not allowed — split into two volumes |
Page count here means the final, typeset page count of the book — not your manuscript's word-processor page count, which is usually shorter once it is reflowed into a 5×8 or 6×9 trim with real margins and a serif body font. This is why margin planning has to happen after typesetting, not before: you cannot know your gutter requirement until you know how many pages the finished interior actually runs.
What "outside, top, bottom" mean and safe defaults
- Outside margin (away from the spine, where the page edge is trimmed): KDP's floor is 0.25 in, but anything under about 0.5–0.625 in reads as cramped once you add a running head or folio near the edge.
- Top margin: needs room for a running head (author name or chapter title) above the first line of body text without crowding it. 0.75–0.9 in is a common professional range.
- Bottom margin: needs room for a folio (page number) below the last line. 0.7–0.8 in is typical.
- Bleed: KDP's interior file for a book with no full-bleed images (pure prose) should have no bleed at all — adding bleed to a no-bleed manuscript is a common self-publish mistake that shifts every margin by 0.125 in on the wrong sides.
Why this trips people up
Two failure modes show up constantly in self-publishing forums: (1) using one fixed gutter for the whole book regardless of final length, which works for a 200-page novella and then silently fails a 600-page fantasy doorstop; (2) measuring margins from a manuscript's Word page count instead of its final typeset page count, which is almost always wrong because reflow changes page count substantially. Both are solved by generating the interior first, reading its actual page count, and only then locking the gutter — or by using a typesetter that does that lookup automatically per book.
Our <a href="/book-interior-service/">Book Interior Formatting Service</a> does exactly this: it lays out your manuscript, counts the real finished pages, and picks the correct KDP gutter from that count automatically (plus a small safety buffer above KDP's stated minimum), then reports the chosen margins next to KDP's minimums in a layout report so you can check the numbers before you upload anything. The same logic is available as a pay-per-call API at <a href="/docs-api/#typeset">POST /v1/typeset</a> for anyone building their own publishing pipeline.