IMAGE RESOLUTION GUIDE
DPI vs PPI: what actually matters?
PPI describes how image pixels relate to physical inches. DPI describes printer dots. The terms are often mixed together, but the pixels in your file are what determine how much image detail you have.
The short answer
PPI means pixels per inch and is the useful measurement for a digital image at a physical print size. DPI means dots per inch and describes how a printer places ink or toner. When a website asks for a “300 DPI image,” it usually means an image with enough pixels to print at 300 PPI.
What is PPI?
PPI connects a digital image’s pixel dimensions to a physical size. A 3,000-pixel-wide image printed 10 inches wide contains 300 pixels in every inch, so it prints at 300 PPI.
PPI = pixels ÷ inchesprint inches = pixels ÷ PPIPPI is not a fixed quality score by itself. You need the pixel dimensions and intended print size as well. The same file can be 300 PPI at 10 inches wide or 150 PPI at 20 inches wide.
What is DPI?
DPI describes physical printer dots. Printers can use multiple dots of ink to reproduce one image pixel, so a printer may operate at a much higher DPI than the image’s PPI. The exact relationship depends on the printer, paper, ink, and screening process.
For image preparation, concentrate on pixel dimensions and PPI. Your printer or print lab controls the device-specific DPI settings.
How PPI changes print size
This example uses a 3,000 × 2,400 pixel image. The pixels never change—only the density and resulting physical size do.
| Resolution | Print size | Typical use |
|---|---|---|
| 300 PPI | 10 × 8 in | Close-viewed photo print |
| 240 PPI | 12.5 × 10 in | Very good general printing |
| 150 PPI | 20 × 16 in | Poster viewed farther away |
Does changing DPI improve image quality?
No. Changing only the embedded resolution value does not create pixels, sharpen the subject, or recover lost detail. It changes the suggested physical size used by compatible software.
Resampling is different: it changes the pixel dimensions by removing or estimating pixels. Enlarging can be useful for workflow requirements, but it cannot recreate genuine source detail that was never captured.
Which value should you use?
- 300 PPI: a common target for photographs, books, and artwork viewed up close.
- 240 PPI: often excellent for photo printing while allowing a slightly larger print.
- 150 PPI: often workable for posters and large displays viewed from farther away.
Always follow the requirements of your print provider when they specify dimensions, resolution, color, bleed, or file format.
CHECK YOUR FILE
See the pixels and embedded resolution
Use PixGauge to read a JPG, PNG, or WebP locally and calculate its practical print sizes.