What this error means
KDP's pre-flight inspects every embedded image in your PDF and calculates the effective DPI — pixel dimensions divided by the size the image actually prints at. Anything below 300 DPI is flagged. The rejection email usually says "One or more images in your manuscript are below 300 DPI" and may list specific page numbers.
Effective DPI is what matters, not the source file's DPI metadata. A 600×600 px image at a 1" square print size is 600 DPI. The same image stretched to fill a 3" square is only 200 DPI — and KDP rejects it. This is why a "high resolution" image can still fail: it depends on how big you place it on the page.
Why it happens
The most common cause is using web-sourced images. Google Image search, Unsplash thumbnails, and screenshots from a Retina display all default to 72 or 96 DPI. They look crisp on screen because monitors are low DPI, but print rejects them.
Word and Google Docs compress images on export. Word's default PDF export downsamples images to 220 DPI unless you toggle "High quality printing" in PDF options. Google Docs is worse — it caps export to roughly 150 DPI.
Canva exports at 300 DPI only if you pay for the Pro tier and select "PDF Print". The free tier exports at 96 DPI.
Resizing images larger in the document is the silent killer. You drop in a 1200 px image, then drag the handle to make it fill the page — and the effective DPI halves.
Vellum and Atticus respect the source image's DPI, so the problem there is almost always the original asset, not the export.
The fix
Step 1: Identify which images are too small. Open the PDF in Acrobat Pro → Tools → Print Production → Preflight → "List page objects, grouped by type" → expand the Images section. Each image's effective DPI is listed.
Step 2: Source replacements. For each flagged image:
- Photos: re-shoot at maximum camera resolution, or use a stock site that offers a "print" download (Shutterstock, Adobe Stock, Getty all do)
- Diagrams and charts: rebuild as vector in Illustrator, Affinity Designer, or Inkscape, then export as 600 DPI PNG (vector → PNG always works because you choose the export DPI)
- Screenshots: never use a screenshot in print — recreate the content as a styled diagram
Step 3: If you absolutely must use an existing image, upscale it carefully. Photoshop's "Preserve Details 2.0" or Topaz Gigapixel AI can take a 1200 px image to 2400 px with acceptable results — but only one zoom level. Don't upscale 4×.
Step 4: Place the new image at its native size. Don't drag-resize larger in Word — insert at the correct dimensions.
Step 5 (Word): File → Options → Advanced → Image Size and Quality → tick "Do not compress images in file" and set "Default resolution" to "High fidelity". Then File → Save As PDF → Options → tick "ISO 19005-1 compliant (PDF/A)" and "High quality printing".
Step 6 (Canva Pro): Download → PDF Print → enable "Crop marks and bleed" only if you've designed for bleed, and tick "Flatten PDF".
Step 7 (InDesign): File → Export → PDF/X-1a:2001 preset. Under Compression, set colour and greyscale images to "Do Not Downsample" and image quality to "Maximum".
Step 8: Re-open the exported PDF and re-check DPI as in step 1.
How to pre-flight it
Our free KDP Readiness Score reports the effective DPI of every embedded image in your PDF, page by page, with thumbnails. It also flags 30 other rules KDP enforces. If everything is green, the file will pass KDP's automated check.
Related errors
- KDP error: low-resolution cover under 2560×1600
- KDP error: embedded images too large
- KDP error: RGB images instead of CMYK
FAQ
Does KDP really reject 299 DPI images? In practice their checker rounds, and 285+ DPI usually passes. But anything below 250 is a hard fail. Aim for 300+ to be safe.
What about cover images — same 300 DPI rule? Cover is measured differently: KDP wants 2560×1600 px minimum for ebook covers, and 300 DPI at the full wrap size for print covers.
Can I use vector images instead? Yes — embedded SVG or vector PDF content is resolution-independent and always passes the DPI check. Use vector for logos, charts, and diagrams whenever possible.
Will KDP downsample my 600 DPI images? KDP doesn't downsample your interior in print-on-demand, but Kindle Direct does compress ebook images. For print, higher DPI is preserved.
