# What is the gutter in a book?

The gutter is the inside margin of a printed page, the side that runs into the binding. It has to widen as a book gets thicker, because more of the page curves out of sight. KDP sets a minimum for each page count, from 0.375 in up to 0.875 in.

Last reviewed 30 October 2026. Web page: https://chapbook.ink/glossary/gutter/

## What it means in practice

KDP's minimum inside margin, by the book's page count:

| Pages | Minimum inside margin |
|---|---|
| 24–150 | 0.375 in |
| 151–300 | 0.5 in |
| 301–500 | 0.625 in |
| 501–700 | 0.75 in |
| 701–828 | 0.875 in |

The gutter swaps sides from page to page: it is on the left of a right-hand page and on the right of a left-hand one. So the left and right margins of a printed page differ, and they swap on the next page.

## How Chapbook uses it

A [paperback interior](/manual/launch-and-export/#make-a-paperback-interior) adds KDP's minimum for its page count to the outside margin, so the inside margin is always the wider one. Widening the gutter can change the page count, so Chapbook lays the book out again until the two agree. Its paperback stops at the end of the third band in the table.

The preflight report under the file lists its margins beside KDP's minimums. The sample on this page is a digital PDF with no binding, so its left and right margins match.

## Made with Chapbook: The Pricing Playbook

The Pricing Playbook: How founders set a price they can defend, by Jane Founder. Nonfiction book, 9,862 words, 43 pages. A sample generated from one brief and exported unedited; it is not a customer's book. Read every page: https://chapbook.ink/examples/nonfiction/

The brief:

> A repeatable method for pricing software: customer interviews, a value metric, tiering, and setting numbers you can defend. Promise: A repeatable method for setting a price you can defend to customers, investors and yourself, validated by ten customer interviews in a week. Reader: A founder who priced by guessing or by copying a competitor and now has to defend or change the number. Voice: Direct second person with occasional first person; worked examples with fictional companies; tables where they clarify; no invented statistics or named studies: reason from mechanics and examples.

The outline the planner proposed:

1. Introduction (620 words)
2. Why Guessing Fails (1,014 words)
3. What You Are Actually Selling (1,004 words)
4. Interview Ten Customers (1,088 words)
5. Choose the Value Metric (979 words)
6. Draft Three Tiers (1,076 words)
7. Set the Numbers (1,130 words)
8. Say the Price Out Loud (1,063 words)
9. Revisit Every Quarter (994 words)
10. Conclusion (384 words)
11. Appendix: The Interview Script (475 words)

## Questions

### Is the gutter the same as the inside margin?

At KDP, yes. Its help page, checked on 30 October 2026, says every page has one inside margin, also called the gutter.

### Why does the gutter depend on the page count?

A thicker book doesn't open as flat, so more of each page disappears toward the spine. KDP's minimum rises in steps as the page count grows.

## Sources

- [Amazon KDP, “Set Trim Size, Bleed, and Margins”](https://kdp.amazon.com/en_US/help/topic/GVBQ3CMEQW3W2VL6)