Check PDF Image Resolution Online
Printers, self-publishing platforms and design clients all ask for 300 DPI, but a PDF doesn't show you the resolution of the images inside it. This checker lists every image on every page with its pixel size, the size it's placed at, and its effective DPI, so you can find the one blurry photo before it goes to print.
What Is Effective DPI?
An image's effective DPI depends on how large it's placed in the document, not just its pixel count:
Effective DPI = pixel width ÷ placed width in inches
The same 1,800 pixel wide photo is 300 DPI when placed 6 inches wide, but only 150 DPI when stretched to 12 inches. That's why a PDF can contain sharp and blurry versions of the same image.
What DPI Should a PDF Be?
| Use | Recommended DPI |
|---|---|
| Books, magazines, brochures, KDP and IngramSpark | 300 |
| Posters and banners viewed from a distance | 150–200 |
| On-screen PDFs and email | 72–150 |
How to Fix Low-DPI Images
- Replace the image with a higher-resolution original or a larger export.
- Place it smaller on the page; halving the placed width doubles the effective DPI.
- Avoid upscaling. Enlarging a low-resolution image in an editor raises the pixel count without adding real detail.
- Check your export settings. "Smallest file size" PDF presets often downsample images to 150 DPI or less; use a print or PDF/X preset instead.
Preparing a book? The KDP cover calculator and IngramSpark cover template check DPI together with size, bleed and fonts.