Pixel Density Explained
Pixel density (PPI — pixels per inch) measures how tightly packed the pixels are on a display. Higher PPI means sharper text, smoother edges, and more screen real estate at a given physical size. This guide explains PPI, physical vs. logical resolution, DPR (device pixel ratio), and how to choose the right pixel density for your use case.
PPI tiers
Under 100 PPI
Visible pixels at normal distance. Typical of 24" 1080p monitors. Acceptable for office work, not for photo editing.
100-150 PPI
Standard density. 27" 1440p (~109 PPI) or 24" 1440p (~122 PPI). Good balance of sharpness and GPU requirements.
150-220 PPI
High density. 27" 4K (~163 PPI) or 15" laptop 4K (~282 PPI). Requires OS scaling (150% or 200%) for usable UI.
220+ PPI (Retina)
Apple Retina territory. 15" MacBook Pro (~220 PPI), phones (400+ PPI). Pixels invisible at normal distance.
Physical vs. logical resolution
Physical resolution is the actual pixel count of your panel (e.g., 3840 × 2160 for 4K). Logical resolution is what the OS renders at — on a high-DPI display, the OS uses scaling (e.g., 150%) so UI elements remain usable. The device pixel ratio (DPR) is the ratio of physical to logical pixels: DPR 1 = standard, DPR 2 = Retina, DPR 3 = high-density mobile.
Web developers care about logical resolution (CSS pixels); hardware folks care about physical resolution. A phone with 1080×2400 physical pixels at DPR 3 has a logical resolution of 360×800 CSS pixels. The resolution checker tool reports both.
Calculate your PPI
Use these tools to measure your display's pixel density:
Calculate your display's PPI
Free, no download, runs in your browser.
Open Screen Size Calculator