What margins does my book need?
Print books need wider inside margins (the gutter, next to the spine) than outside margins, because pages curve into the binding. KDP sets minimums that grow with your page count. This book margin calculator gives you the KDP minimum and two more comfortable presets for any trim size, shows them on a live two-page spread and creates a Word template with mirror margins already set.
KDP minimum margins
| Page count | Inside (gutter) | Outside, top, bottom |
|---|---|---|
| 24–150 | 0.375 in (9.6 mm) | 0.25 in without bleed, 0.375 in with bleed |
| 151–300 | 0.5 in (12.7 mm) | |
| 301–500 | 0.625 in (15.9 mm) | |
| 501–700 | 0.75 in (19.1 mm) | |
| 701–828 | 0.875 in (22.3 mm) |
Minimum vs comfortable margins
KDP minimums are the least you can use, not what looks best. Most professionally designed novels use about 0.125 in more on the inside and 0.5–0.75 in on the outside, with 0.75 in at the top and bottom. Wider margins look more elegant and are easier to hold — but add pages and printing cost. The calculator shows how many pages your manuscript becomes with each option.
How to set margins in Word
- Layout › Size › More Paper Sizes: enter the trim size (or trim + bleed).
- Layout › Margins › Custom Margins › Multiple pages: Mirror margins.
- Enter Inside, Outside, Top and Bottom; set Gutter to 0.
- Or simply download our ready Word template.
Related tools: gutter calculator, book bleed calculator for page size with bleed, page count estimator.
Choose a margin style
- KDP minimum: the smallest margins Amazon KDP accepts. Use only for workbooks or when page count really matters.
- Comfortable: what most printed novels use — room for thumbs and a gutter that keeps words out of the spine.
- Generous: for poetry, gift books and premium nonfiction.
- Custom: type your own values; the calculator warns you if anything is below the KDP minimum.
KDP rules the calculator checks
The inside margin (gutter) 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. Outside, top and bottom margins must be at least 0.25 in without bleed, or 0.375 in with bleed.
Example: 6 × 9 in, 250 pages
The KDP minimum gutter is 0.5 in. The “Comfortable” preset uses 0.625 in inside and outside and 0.75 in top and bottom — safely above the minimum and easy to read.
Download a ready Word template
The Word template (.docx) button gives you a document with the right page size, mirror margins, gutter and font already set. Paste your manuscript in and the layout is correct from page one.
Set margins in your software
Pick your program — Microsoft Word, Google Docs, InDesign, Affinity Publisher, Atticus or Vellum — to see exact steps. In Word, use Layout → Margins → Custom Margins → Mirror margins, put the gutter in “Inside” and leave Word’s separate gutter box at 0 so it isn’t counted twice.
Full rules and common mistakes: KDP margins and gutter size guide.