# Choose your trim size and margins

The trim size is how big your printed book is; the margins are the white space around the words. This page helps you pick both. You'll find them on the **Layout** tab of **Page setup** (in the **Book** menu).

![Screenshot: the Trim size and Margins cards](https://assets.authortools.net/help/screenshot-placeholder.png)
*Screenshot: the Trim size and Margins cards on the Layout tab, with the Gutter set to Auto.*

### Trim size

Choose from **Preset**, or pick **Custom** and type the **Width** and **Height** in inches.

- **5 × 8**, **5.25 × 8** and **5.5 × 8.5** are the usual sizes for a novel. 5.25 × 8 is a good place to start if you're unsure.
- **6 × 9** suits a long book, or one with lots of pictures.
- The larger sizes are for nonfiction, workbooks and illustrated books.

Use the size you'll order from your printer—KDP and IngramSpark both list the sizes they offer. Changing the trim size changes how many words fit on a page, so the page count will change too; the **Estimated pages** figure on the right keeps up as you go.

### Margins

- **Top** — from the top of the page to the first line of text. The header (your name or the book's title) sits in this space, so give it room: ¾ inch is comfortable.
- **Bottom** — from the last line to the foot of the page, where the page number sits.
- **Inside** — the edge at the spine.
- **Outside** — the open edge, where readers' thumbs go. KDP asks for at least ¼ inch (⅜ inch with bleed); ½ inch looks like a proper book.

### The gutter

A thick book curves into its spine, and the words near the fold get hard to read. The gutter is extra room added to the inside margin to keep them clear.

Leave **Auto** ticked and Write works it out from how long the book actually is—⅛ inch up to 150 pages, more as the book grows—and sets the PDF to match. Untick it only if your printer asks for a particular gutter.

### Bleed

Bleed is a little extra paper past the edge of the page that the printer trims away, so a picture or background running to the edge never leaves a white sliver. ⅛ inch is what KDP and IngramSpark ask for. Leave it on even if nothing in your book runs to the edge yet; your margins are measured from the trimmed page, not the bleed, so it doesn't change how the book looks.

When you upload to KDP, choose **Bleed (PDF only)** to match. More on that in [Publish a print PDF](/link/48).

### When something isn't right

Under the preview on the right, Write checks the setup against KDP's print requirements as you type. When everything's fine it says **Clears KDP's print requirements**; when something isn't—a margin too narrow for the page count, say—it says what, and the note goes away once you fix the number it names.