KDP interior guide · 한국어

Why KDP rejected your coloring book interior — and how to fix each error

A practical, numbers-first guide from the team behind Prepressly, a free in-browser KDP interior fixer. Updated 2026.

Almost every coloring-book interior Amazon KDP flags fails for one of five concrete, fixable reasons. Below is each error, the exact number KDP wants, and how to correct it — by hand in any editor, or automatically in your browser.

1. The PDF page size doesn't match your trim

When you pick a trim (say 8.5 × 11 in) in KDP, your uploaded PDF's page dimensions must match it exactly. If your pages are a different size — even slightly — KDP's Print Previewer warns the content will be scaled or won't fit. Screenshot-sized or A4 pages are the usual culprit.

Fix: re-fit every page to the exact trim in points (1 in = 72 pt), so 8.5 × 11 = 612 × 792 pt. Don't just "print to PDF" — that keeps the source page size.

2. Margins: "content extends beyond the printable area" & the gutter

Two separate margin rules trip people up:

Outside (safe) margin

For a no-bleed interior, keep all content at least 0.25 in from every trimmed edge. Line art that runs to the edge on a no-bleed page will be flagged.

Inside (gutter / binding) margin — and why it grows

The gutter is the inside margin swallowed by the spine. KDP's minimum increases with page count, and this is the single most-missed rule on longer coloring books:

Fix: inset content to the correct gutter for your page count. A 40-page book needs 0.375 in; a 200-page book needs 0.5 in or the innermost art disappears into the spine. (Prepressly sizes this for you automatically from your page count.)

3. Images below 300 DPI

KDP recommends 300 DPI. If your source scan or AI export is small and gets enlarged to fill an 8.5 × 11 page, effective DPI drops below 300 and lines print soft or pixelated. 300 DPI at 8.5 × 11 means the image should be about 2550 × 3300 px.

Fix: rasterize each page at a true 300 DPI for the target trim. (True upscaling of a genuinely low-res source is a different problem — see the note in the AI-lines guide below.)

4. Bleed set up wrong (no-bleed vs full-bleed)

Pick one and be consistent:

• No-bleed — the PDF page is the exact trim, art sits inside white safe margins. Right for standard line-art coloring pages.
• Full-bleed — the PDF page is trim + 0.125 in wider and + 0.25 in taller (e.g. 8.5 × 11 → 8.625 × 11.25), and the art runs off all edges. Right for mandala/pattern/zentangle books meant to print edge to edge.

Fix: if any page's art touches the edge, the whole interior must be full-bleed with the correct oversized page — a centered image on a white page is not full-bleed.

5. Faint or gray lines (the quality killer)

This one isn't always a hard rejection, but it's why "accepted" books get 1-star "the pages are too light to color" reviews. Scanned pencil art and — especially — AI-generated line art export as anti-aliased gray, not pure black. On press it prints washed-out.

Fix: force faint/gray strokes to solid pure-black while preserving line weight and detail, and clean scanner speckle. If your art comes from Midjourney or Stable Diffusion, read the dedicated guide below — gray AI lines are their own specific fix.

The pre-upload checklist

• Every page's size = your exact KDP trim (612 × 792 pt for 8.5 × 11).
• No-bleed: content ≥ 0.25 in from every edge. Full-bleed: page = trim + 0.125/0.25 in, art to the edge.
• Inside/gutter margin matches your page count (0.375 in up to 150 pp).
• Images render at 300 DPI for the trim (~2550 × 3300 px at 8.5 × 11).
• Lines are solid pure-black, not gray; speckle removed.
• Grayscale/DeviceGray (not RGB); at least 24 pages; no long runs of blanks.

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