KDP Margin & Gutter Calculator
Enter your page count to get the exact inside (gutter) margin Amazon requires, alongside the flat outer, top, and bottom margins.
Add 0.125" bleed on top of these if any element touches the page edge.
Gutter margin by page count
| Page count | Gutter margin |
|---|---|
| Up to 150 | 0.375" |
| 151–300 | 0.75" |
| 301–500 | 0.875" |
| 501–700 | 0.9" |
| 701+ | 1.0" |
Common questions
What is the gutter margin on KDP?
The inside margin, closest to the spine. It needs to be wider than your other margins because binding eats into that space, and KDP requires a bigger gutter as your page count grows.
What are the outer, top, and bottom margins?
A flat 0.5" on each, regardless of page count. Only the gutter changes.
Do I need extra margin for bleed?
Only if an image or element touches the page edge, add 0.125" bleed. Text-only books usually don't need it.
Why this matters
Too narrow a gutter and your text disappears into the binding on longer books. Too wide and you waste page space unnecessarily. Getting this right the first time saves a reprint proof.
KDP Workspace's free Interior Assembler calculates this automatically alongside your spine width, so your whole layout is consistent.
Try the free tool →