KDP Margins and Gutter Size: The Exact Settings for Every Page Count
Getting margins wrong is one of the most common reasons Amazon KDP rejects a paperback interior — or, worse, prints a book where words disappear into the spine. The rules are simple once you know that the inside margin (the gutter) grows with your page count. Here are the exact settings.
KDP margin requirements (paperback)
| Page count | Inside margin (gutter) | Outside margins — no bleed | Outside margins — with bleed |
|---|---|---|---|
| 24 – 150 | 0.375 in (9.6 mm) | at least 0.25 in (6.4 mm) | at least 0.375 in (9.6 mm) |
| 151 – 300 | 0.5 in (12.7 mm) | at least 0.25 in (6.4 mm) | at least 0.375 in (9.6 mm) |
| 301 – 500 | 0.625 in (15.9 mm) | at least 0.25 in (6.4 mm) | at least 0.375 in (9.6 mm) |
| 501 – 700 | 0.75 in (19.1 mm) | at least 0.25 in (6.4 mm) | at least 0.375 in (9.6 mm) |
| 701 – 828 | 0.875 in (22.3 mm) | at least 0.25 in (6.4 mm) | at least 0.375 in (9.6 mm) |
Source: Amazon KDP paperback formatting guidelines. “Outside margins” means the top, bottom and outer edge of each page.
Why the gutter gets bigger
A thick book does not open flat. The more pages it has, the more of each page curves into the binding. A bigger inside margin keeps your text out of that curve, so readers do not have to force the book open.
Minimum is not the same as recommended
The table shows the minimum KDP will accept. A page with 0.25 in outside margins is legal but looks cramped and leaves no room for the reader’s thumbs. Most professionally printed novels use about 0.5–0.75 in on the outside, top and bottom, and add a little extra to the gutter on top of the minimum.
Example: a 6 × 9 inch novel with 250 pages
- Page count 151–300 → gutter at least 0.5 in (we would use 0.6–0.7 in).
- No bleed → outside margins at least 0.25 in (we would use 0.6 in).
- Top and bottom: 0.6–0.75 in, with room for page numbers and headers.
Our book margin calculator gives you the minimum and a comfortable recommended setting for any trim size and page count, ready to type into Word, Google Docs or InDesign.
Bleed: when your images touch the edge
If any picture or colour runs to the edge of the page, you need a bleed interior. The page is made 0.125 in wider and 0.25 in taller than the trim size (0.125 in extra on the top, bottom and outside edge), and that extra strip is cut off after printing. A 6 × 9 in book with bleed uses pages of 6.125 × 9.25 in. Keep important text inside the safe area, at least 0.375 in from the trimmed edge.
How to set mirror margins in Word
- Layout → Margins → Custom Margins.
- Under Pages, choose Mirror margins.
- Set Inside to your gutter (for example 0.6 in) and Outside, Top and Bottom to your outside margin.
- Leave the separate “Gutter” box at 0 — the inside margin already includes it, so you do not count it twice.
- Export to PDF and check it in KDP’s print previewer before you publish.
5 common margin mistakes
- Using the gutter for the wrong page count. If you add pages later, check the gutter again.
- Adding the gutter twice — once in “Inside” and again in Word’s gutter box.
- Page numbers too close to the edge. Headers and footers must stay inside the margins too.
- Bleed images in a no-bleed file. Either add bleed or keep images inside the margins.
- Forgetting that page count changes the spine. More pages also means a wider cover spine — check it with the spine width calculator.
Not sure of your page count yet?
Estimate it from your word count, trim size and font with the word count to pages calculator, then set your margins with the book margin calculator.
Rules shown are from Amazon KDP’s paperback guidelines. Always confirm the current requirements in KDP’s help pages and preview your file before publishing.
Frequently asked questions
What gutter size does KDP require?
It depends on page count: 0.375 in for 24–150 pages, 0.5 in for 151–300, 0.625 in for 301–500, 0.75 in for 501–700 and 0.875 in for 701–828 pages.
What are the outside margins for KDP?
At least 0.25 in (6.4 mm) on the top, bottom and outside edge without bleed, and at least 0.375 in (9.6 mm) with bleed. Most printed books use wider outside margins (around 0.5–0.75 in) because they are easier to read.
How much bleed does KDP need?
For a bleed interior the page size is 0.125 in wider and 0.25 in taller than the trim size (0.125 in extra on the top, bottom and outside edge). A 6 × 9 in book with bleed uses 6.125 × 9.25 in pages.
