PPI calculator
Short answer
Divide the diagonal in pixels by the diagonal in inches: a 27-inch 4K screen has √(3840² + 2160²) ÷ 27 = 163.2 ppi; a 27-inch 1440p screen 108.8 ppi.
Common screens
| Screen | Pixel density |
|---|---|
| 13.3 inch 1080p | 165.6 ppi |
| 15.6 inch 1080p | 141.2 ppi |
| 24 inch 1080p | 91.79 ppi |
| 24 inch 1440p | 122.4 ppi |
| 27 inch 1440p | 108.8 ppi |
| 27 inch 4K | 163.2 ppi |
| 32 inch 4K | 137.7 ppi |
| 34 inch ultrawide | 109.7 ppi |
| 55 inch 4K TV | 80.11 ppi |
| 65 inch 4K TV | 67.78 ppi |
More about pixels
Questions
At desk distance, around 110 ppi looks sharp at 100% scaling and 140 ppi or more looks crisp with scaling; phones sit at 400 ppi and up because they are held close.