KDP requires all images in your interior PDF to be at least 300 DPI (dots per inch) at their printed size. If an image looks fine on screen but prints blurry, it’s almost certainly below 300 DPI. KDP’s file review catches this and either rejects the file or flags it with a quality warning. The most common cause: using images that look sharp on a 72–96 DPI screen but are only 150–200 DPI when printed at book size. A full-page image at 5.5”×8.5” needs to be at least 1,650 × 2,550 pixels.
Understanding DPI for print
DPI = pixels ÷ printed size in inches.
A 1,000-pixel-wide image printed at:
- 10 inches wide = 100 DPI (blurry, rejected)
- 5 inches wide = 200 DPI (soft, may be flagged)
- 3.33 inches wide = 300 DPI (sharp, accepted)
The same image file can be 300 DPI or 72 DPI depending on how large you print it. This is why an image that looks fine on your monitor can fail KDP’s print review.
Minimum image sizes for common trims
| Trim Size | Full-Page Image (min pixels) | Half-Page Image (min pixels) |
|---|---|---|
| 5” × 8” | 1,500 × 2,400 | 1,500 × 1,200 |
| 5.5” × 8.5” | 1,650 × 2,550 | 1,650 × 1,275 |
| 6” × 9” | 1,800 × 2,700 | 1,800 × 1,350 |
| 8.5” × 11” | 2,550 × 3,300 | 2,550 × 1,650 |
How to check your image resolution
Before building the PDF
Right-click any image file → Properties (Windows) or Get Info (Mac) → check pixel dimensions. Divide by the size it will print at.
In the final PDF (Adobe Acrobat Pro)
Tools → Print Production → Output Preview → check “Object Inspector.” Click on any image to see its effective resolution at print size.
Quick math
If you know the image width in pixels and the width it’ll be on the page:
DPI = pixel width ÷ printed width in inches
Example: 800px image printed 4 inches wide = 200 DPI → too low
How to fix low-resolution images
Option 1: Use a higher-resolution source
The best fix. Go back to the original photo or illustration and export at a larger size. If you’re using stock photos, download the largest available size. Phone photos taken in the last 3 years are typically 3,000–4,000px wide — more than enough for any book trim.
Option 2: Reduce the printed size
If you can’t get a larger source, make the image smaller on the page. An 800px image printed at 2.5” wide = 320 DPI — above the minimum.
Option 3: AI upscaling (last resort)
Tools like Topaz Gigapixel, Real-ESRGAN, or Photoshop’s Neural Filters can upscale images. Results vary — they work well for photos but poorly for text, line art, or diagrams. KDP may still flag AI-upscaled images if the quality is poor.
What NOT to do: Simply change the DPI metadata in your image editor without changing the pixel count. Setting a 500px image to “300 DPI” in Photoshop’s Image Size dialog (with “Resample” unchecked) doesn’t add pixels — it just changes the metadata. KDP checks the actual pixel density at print size, not the metadata.
Cambric warns you if any image is below 300 DPI at print size before you export — no more upload-wait-reject cycles.
Get Cambric — $199
Special cases
Scene break ornaments and decorative elements
Small decorative images (scene break ornaments, chapter heading decorations) need to be 300 DPI at their printed size too. A 1-inch-wide ornament needs to be at least 300px. Most stock ornament sets ship at 600+ DPI — you’re usually fine.
Black and white line art
Line art (drawings with no shading) looks better at 600–1200 DPI. At 300 DPI, diagonal lines and curves can show visible stairstepping. KDP accepts 300 DPI minimum, but aim higher for line art if possible.
Charts and diagrams
Export charts from your data tool at the largest size possible. Google Sheets and Excel charts exported as images are often surprisingly low resolution. Export as SVG if possible, then convert to a high-res PNG.
Related guides
- KDP file rejection fixes — all common errors
- Book bleed explained — image placement with bleed
- Format a children’s book — image-heavy layout guide
- KDP Book Calculator — verify specs