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KDP margins, gutter & bleed: the cheat sheet
Every number Amazon KDP checks on your interior PDF — minimum gutter by page count, outside margins with and without bleed, and the exact bleed math — on one page. These are the same specs our production pipeline typesets to.
The three terms, in one picture
Gutter is the inside margin — the edge that disappears into the binding. It has to be bigger than the other margins because the glue and curve of the spine eat into it, and thicker books curve more (hence the page-count table below).
Outside margins are the top, bottom, and outer edges — the white frame the trimming blades are allowed to wander into. KDP requires at least 0.25″, or 0.375″ if your file has bleed elements.
Bleedis an extra 0.125″ of printed area past the trim line, only needed when ink is supposed to run to the very edge of the page. It exists because trimming isn’t perfectly precise: without bleed, a millimeter of drift leaves a white sliver on your full-page image.
Minimum gutter by page count
This is the table KDP actually enforces. The gutter is measured from the binding edge to your content, and the minimum steps up as the book gets thicker.
| Page count | Minimum gutter (inside margin) | Minimum outside margins |
|---|---|---|
| 24 – 150 pages | 0.375″ | 0.25″ (0.375″ with bleed) |
| 151 – 300 pages | 0.5″ | 0.25″ (0.375″ with bleed) |
| 301 – 500 pages | 0.625″ | 0.25″ (0.375″ with bleed) |
| 501 – 700 pages | 0.75″ | 0.25″ (0.375″ with bleed) |
| 701 – 828 pages | 0.875″ | 0.25″ (0.375″ with bleed) |
Ranges are for black & white paperbacks, which KDP prints from 24 to 828 pages. Hardcovers run 76 to 550 pages and use the same margin minimums for their range.
The bleed math
KDP bleed is 0.125″ per edge, added to the top, bottom, and outside edges — not the gutter side, because that edge is bound, not trimmed. So a page with bleed grows by 0.125″ in width and 0.25″ in height:
| Trim size | PDF page size with bleed |
|---|---|
| 6″ × 9″ | 6.125″ × 9.25″ |
| Any trim W × H | (W + 0.125″) × (H + 0.25″) |
Only add bleed if artwork genuinely runs to the page edge. A text-only interior should be exported at the plain trim size with no bleed at all — that’s the most common setup and the least error-prone.
A comfortable working set (what we typeset to)
KDP’s numbers are bare minimums — a book set exactly at them feels cramped. For a 6″ × 9″ interior, our production default is 0.75″ top and bottom, 0.5″ outside, and the gutter from the table above for the book’s page count. That sits comfortably clear of every minimum, gives running heads and page numbers room to breathe, and produces a text block that reads like a traditionally published page.
Setting mirrored margins in Word
Because the gutter swaps sides on facing pages — left edge on right-hand pages, right edge on left-hand pages — you need mirrored margins, not a fixed left/right pair. In Word: Layout → Margins → Custom Margins, set Multiple pages: Mirror margins, then enter your top, bottom, and outside values and put the gutter value in the dedicated Gutter field (Gutter position: Left). Word then adds the gutter to the inside edge of every page automatically. Set the page size itself under Layout → Size to your exact trim, e.g. 6″ × 9″.
Why KDP rejects interiors
- Live content in the trim or bleed zone. Text or critical artwork sitting inside the margin minimums — or drifting into the 0.125″ that gets cut off — triggers the print checker. Keep everything you need readable inside the margins.
- Gutter too small for the page count. A 0.5″ gutter is fine at 280 pages and a violation at 320. Books that grow during revisions cross a threshold without anyone re-checking the margins.
- Page size doesn’t match the chosen trim. A PDF exported at US Letter for a 6″ × 9″ trim, or a with-bleed file (6.125″ × 9.25″) uploaded for a no-bleed setup — either mismatch causes rejections or bad scaling.
And once the interior is final, remember the wrap-around cover has its own math — your cover has its own math →
Or never touch a margin field.
publish.ai typesets your interior to these exact specs automatically — gutter sized to your final page count, print-ready PDF at the correct trim, plus a validated EPUB, cover, Amazon listing copy, and launch graphics. One upload, minutes, from $29.99.
Common questions
Do I need bleed for my KDP book?＋
Only if something printed — a photo, illustration, or color background — is meant to run all the way to the edge of the page. Text-only interiors should not use bleed: submit them at the plain trim size (e.g. 6″ × 9″) with everything inside the margins. Adding bleed to a text-only book just invites sizing errors.
What gutter size does KDP require?＋
It depends on page count. KDP's minimum inside (gutter) margin is 0.375″ for 24–150 pages, 0.5″ for 151–300, 0.625″ for 301–500, 0.75″ for 501–700, and 0.875″ for 701–828 pages.
Does the gutter change if I add pages?＋
Yes. The minimum gutter steps up when your page count crosses 150, 300, 500, or 700 pages. A 298-page book needs 0.5″; add a preface that pushes it to 302 pages and the minimum becomes 0.625″. Always confirm the final page count before locking your margins — and remember any interior change also changes your cover's spine width.
What size is a 6×9 page with bleed?＋
6.125″ × 9.25″. KDP bleed is 0.125″ per edge, applied to the top, bottom, and outside edges only — never the gutter side. So the width grows by one bleed (6″ + 0.125″) and the height by two (9″ + 0.25″).
What are KDP's page count limits?＋
Black & white paperbacks can be 24 to 828 pages; hardcovers must be 76 to 550 pages. Other ink and paper combinations have their own ranges, so check KDP's specs if you're printing in color.