DPI and Resolution Explained — What Every Designer Should Know

DPI vs PPI

DPI (Dots Per Inch) — Refers to the physical dots a printer puts on paper per inch. Only relevant for printing.

PPI (Pixels Per Inch) — Refers to the number of pixels displayed per inch on a screen. This is what digital images actually have.

In practice, people use "DPI" to mean both. When someone says "a 300 DPI image," they usually mean 300 PPI.

Resolution for Print

Quality Level	DPI	Use Case
Low quality	72 DPI	Screen-only, not for print
Draft quality	150 DPI	Internal documents, drafts
Standard quality	300 DPI	Professional printing
High quality	600+ DPI	Fine art, detailed graphics

Resolution for Web

Screen resolution is measured in pixels, not DPI. A "72 DPI" and "300 DPI" version of the same 1920x1080 image look identical on screen. Only the pixel dimensions matter for web.

Calculating Print Size

Print size = Pixel dimensions / DPI

A 3000x2000 pixel image:

• At 300 DPI: 10 x 6.67 inches (25.4 x 16.9 cm)
• At 150 DPI: 20 x 13.33 inches (50.8 x 33.9 cm)
• At 72 DPI: 41.67 x 27.78 inches (not recommended for print)

Common Mistakes

1. Upscaling to increase DPI — Adding pixels does not add detail. A blurry 72 DPI image upscaled to 300 DPI is still blurry.
2. Using web images for print — A 800x600 image looks fine on screen but prints at only 2.67 x 2 inches at 300 DPI.
3. Ignoring DPI requirements — Some services reject files below their minimum DPI requirement.