KDP Interior Formatting Guide: Margins, Gutter, Bleed & Trim

Interior formatting is where most first KDP uploads fail — not the writing, not the cover, but a gutter that's 0.125″ too small or a PDF page that doesn't match the trim size. This guide covers the exact settings Amazon checks, in the order you should set them, and ends with a free tool that applies all of it to your own file.

1. Lock Your Trim Size First

Everything else — margins, bleed, page count, cover dimensions — derives from trim size, so choose it before formatting a single page. 6″ × 9″ is the default for fiction and nonfiction, 8.5″ × 11″ for coloring and activity books, 5.5″ × 8.5″ for compact journals. See the full breakdown in our trim size guide. Your PDF page size must equal the trim size exactly (plus bleed, if used) — a 6″ × 9″ book submitted on US-Letter pages is an automatic rejection.

2. Set the Gutter by Page Count

The inside margin (gutter) must grow with page count because thicker books curve more deeply into the binding. These are the KDP minimums:

Outside, top, and bottom margins must be at least 0.25″ (0.375″ on pages with bleed). The classic mistake is setting one fixed gutter and then growing the book past a threshold — a 320-page book formatted with a 0.5″ gutter will bounce.

3. Bleed — Only If Art Reaches the Edge

If any artwork should print to the very edge of the page, the file needs bleed: the page size grows by 0.125″ on the top, bottom, and outer edges, and the art extends into that zone. Text-only books skip bleed entirely. Full rules and diagrams are in the bleed and margins guide.

4. Fonts, Images, and Page Numbers

• Embed every font. Un-embedded fonts are a silent rejection cause — most PDF exporters have an “embed fonts” option; verify it's on.
• Images at 300 DPI at their printed size. A 1000px-wide image stretched across an 8.5″ page prints at ~118 DPI and will flag a quality warning.
• Page numbers belong in the outer margin area, inside the live zone, and traditionally skip front matter. Odd pages are always right-hand pages.
• Start chapters on the right (odd-numbered pages) for a traditional feel — optional, but it's what readers expect in print.

5. The Rejection Reasons That Catch Everyone

• Gutter too small for the final page count (the #1 cause).
• PDF page size doesn't match the trim size selected in KDP.
• Text or page numbers crossing into the margin zone.
• Bleed art that doesn't actually extend past the trim line.
• Fonts not embedded, or images under 300 DPI.

Every one of these is mechanically checkable before upload — which is exactly what the next section does for you.

Skip the Manual Work: Format and Check It Free

KDPBuilder's free KDP interior PDF formatter takes a DOCX, PDF, JPG, or PNG, applies your chosen trim size with the correct gutter, margins, and bleed from the tables above, runs a compliance report (page dimensions, margins, DPI, safe zones), and exports a print-ready interior PDF — free up to 120 pages, no watermark. If you'd rather generate a book from scratch — manuscript, interior, and cover together — that's what the full KDP Builder platform does; you can inspect a complete sample package first.

Frequently Asked Questions