---
title: "What Is the Gutter Margin in a Book?"
description: "What the gutter or inside margin of a printed book is, why KDP's minimum grows with page count, and how to set it without losing words in the fold."
url: "https://www.superebook.ai/glossary/gutter"
updated: "2026-10-20"
---

# Gutter (inside margin)

**Definition.** The gutter is the inside margin of a printed book: the space between the text and the fold where pages meet the spine. KDP sets a minimum gutter that grows with the page count, because a thicker book curves more at the binding, and text set too close to the fold disappears into it.

Sources checked October 20, 2026.

## How it works

KDP's margin table sets the minimum inside margin in steps by page count, from its shortest books to its longest, while the top, bottom and outside margins have a single minimum that is larger for books with bleed. Because left and right pages are bound on opposite sides, the gutter sits on the right of a left-hand page and on the left of a right-hand page. Some software has separate fields for the inside margin and the gutter; KDP's advice is to enter the same value in both.

## An example

A short workbook and a long handbook with the same trim fall into different rows of KDP's table, and the handbook's minimum gutter is larger. If the workbook later grows past the row's upper limit because you add chapters, its interior has to be reset with the wider gutter before you upload it again: KDP warns that a file without proper sizing may be rejected on upload or print badly.

## Common mistakes

Using one margin all round, copied from a document template, so the outside margins are generous and the inside one is too narrow. Adding pages without checking whether the book has crossed into a new row of the margin table. And running a two-page image across a spread without allowing for the fold, where the middle of the picture is lost.

## Questions

**Is the gutter the same as the inside margin?** Yes. KDP's help page calls the inside margin the gutter. Where software has fields for both, KDP asks you to enter the same value in each.

**Why does a longer book need a wider gutter?** A thicker book doesn't open as flat, so more of each page curves into the binding. KDP's minimum inside margin rises with the page count to keep text out of the fold.

## Sources

- [KDP: Set Trim Size, Bleed, and Margins](https://kdp.amazon.com/en_US/help/topic/GVBQ3CMEQW3W2VL6): The inside margin, also called the gutter; minimum margins by page count; the outside margins with and without bleed; entering the same value for inside margin and gutter.

## Related terms

- [Trim size](https://www.superebook.ai/glossary/trim-size.md)
- [Bleed](https://www.superebook.ai/glossary/bleed.md)
- [Spine width](https://www.superebook.ai/glossary/spine-width.md)

## Read next

- [Word count to pages converter](https://www.superebook.ai/tools/word-count-to-pages-converter.md)
- [Self-publishing cost calculator](https://www.superebook.ai/tools/self-publishing-cost-calculator.md)
- [All glossary terms](https://www.superebook.ai/glossary.md)