PPI Calculator
Enter a screen's diagonal size and pixel resolution to get its PPI (pixels per inch), pixel pitch, and how sharp it will look. PPI = √(widthPx² + heightPx²) ÷ diagonal — this tool does the math for any monitor, laptop, or TV.
Pixel density
108.8 PPI
Pixel pitch
0.2335 mm
Dots per cm
42.8
Total pixels
3.7 MP
A 27-inch 2560×1440 panel is about 23.53 in wide and 13.24 in tall. Standard density — sharp at typical desk distance, usually runs at 100% scaling.
How PPI is calculated
Pixel density is the diagonal pixel count divided by the diagonal in inches. First find the diagonal resolution with the Pythagorean theorem — √(widthPx² + heightPx²) — then divide by the screen's physical diagonal. A 27-inch 2560 × 1440 monitor is √(2560² + 1440²) ÷ 27 ≈ 109 PPI. Pixel pitch, the spacing between pixels, is simply 25.4 ÷ PPI millimeters.
Common monitor PPI reference
| Monitor | Resolution | Pixel density |
|---|---|---|
| 24-inch 1080p | 1920 × 1080 | 92 PPI |
| 27-inch 1440p | 2560 × 1440 | 109 PPI |
| 27-inch 4K | 3840 × 2160 | 163 PPI |
| 32-inch 4K | 3840 × 2160 | 138 PPI |
| 34-inch ultrawide | 3440 × 1440 | 110 PPI |
| 49-inch 32:9 | 5120 × 1440 | 109 PPI |
| 16-inch laptop | 2560 × 1600 | 189 PPI |
Frequently asked questions
How do you calculate PPI (pixels per inch)?
PPI = √(widthPx² + heightPx²) ÷ diagonalInches. Take the diagonal resolution in pixels (the hypotenuse of the width and height in pixels) and divide by the screen's diagonal in inches. For example, a 27-inch 2560×1440 monitor is √(2560² + 1440²) ÷ 27 ≈ 109 PPI.
What is a good PPI for a monitor?
For a desktop monitor at normal viewing distance, roughly 90–120 PPI is comfortable at 100% scaling. Below ~90 PPI text looks soft up close; above ~150 PPI you usually want OS scaling so the interface stays readable. 27-inch 1440p (~109) and 32-inch 4K (~138) are common sweet spots.
Is higher PPI always better?
Not automatically. Higher PPI means sharper text and images, but it also means the interface renders smaller, so high-density panels usually need display scaling. Two monitors on one desk with very different PPI can also make windows jump size when you drag them across screens.
What is pixel pitch?
Pixel pitch is the distance between the centers of two adjacent pixels, in millimeters: pixel pitch = 25.4 ÷ PPI. A smaller pixel pitch means a denser, sharper display. A 109 PPI panel has a pixel pitch of about 0.233 mm.