Screen Size Calculator: Find Your Screen PPI and Dimensions
Enter resolution and diagonal to get PPI, width, height, aspect ratio and dot pitch of any screen.
Detecting your screen...
How to use the screen size calculator
- Press Use my screen resolution to fill in your screen pixels, or type any resolution, for example 2560 x 1440.
- Type the diagonal in inches from the spec sheet. Pick a preset if you are not sure.
- Read the PPI, the real width and height in inches and centimeters, the aspect ratio and the dot pitch.
- Press Use this PPI for the ruler to calibrate the online ruler on this screen.
Common screens and their PPI
| Screen | Resolution | PPI | Width x height |
|---|---|---|---|
| 24 inch monitor | 1920 x 1080 | 92 | 53.1 x 29.9 cm |
| 27 inch monitor | 2560 x 1440 | 109 | 59.8 x 33.6 cm |
| 27 inch 4K monitor | 3840 x 2160 | 163 | 59.8 x 33.6 cm |
| 15.6 inch laptop | 1920 x 1080 | 141 | 34.5 x 19.4 cm |
| MacBook Air 13.6 inch | 2560 x 1664 | 224 | 29.0 x 18.8 cm |
| iPhone 16 | 1179 x 2556 | 460 | 6.5 x 14.1 cm |
The formulas
- Diagonal in pixels = square root of (width x width + height x height).
- PPI = diagonal in pixels / diagonal in inches.
- Width in inches = diagonal x width / diagonal in pixels. Height works the same way.
- Dot pitch in mm = 25.4 / PPI.
Screen sizes are measured on the diagonal of the visible area, not including the frame. Two screens with the same diagonal but different aspect ratios have different widths and heights.
Frequently asked questions
How do I find my screen size?
Check the model on the box, in the manual or in your system settings, then read the diagonal from the spec sheet. Or measure the visible screen corner to corner with a tape measure, without the bezel.
How is PPI calculated?
PPI is the diagonal in pixels divided by the diagonal in inches. The diagonal in pixels is the square root of width squared plus height squared. For a 24 inch 1920 x 1080 monitor that is 2203 / 24, about 92 PPI.
What is a good PPI?
For a desktop monitor 90 to 110 PPI looks fine at normal distance and 140 or more looks sharp. Laptops are often 140 to 220 PPI, and phones 400 to 500 PPI.
Why does my ruler PPI differ from this number?
Browsers draw in CSS pixels. On a screen with a pixel ratio of 2 or 3, one CSS pixel uses several hardware pixels, so the ruler PPI is the hardware PPI divided by the pixel ratio. The calculator does this for you when you press Use this PPI for the ruler.
What is dot pitch?
Dot pitch is the distance between two neighbouring pixels in millimeters. Smaller dot pitch means a sharper screen. It is 25.4 divided by the PPI.