MeasureSparkScreen & ruler
Screen PPI Calculator
Enter the horizontal and vertical resolution shown in your display settings, plus the advertised diagonal size.Enter your measurements
PPI = diagonal pixel count divided by diagonal size in inches.
How this estimate works
PPI = diagonal pixel count divided by diagonal size in inches.
Measure twice and use the same unit throughout. Product coverage, material density, installation patterns, and local requirements can change the quantity you need.
Quick answer
Screen PPI equals the diagonal pixel count divided by the screen diagonal in inches. Use the panel's native pixel resolution and the advertised viewable diagonal.
Worked example
For a 1920 × 1080 display, the diagonal is 2,202.9 pixels. Dividing by a 24-inch diagonal gives about 91.8 PPI.
Assumptions
- Horizontal and vertical values are the panel's native resolution.
- The diagonal measurement is the viewable screen size in inches.
- Pixels are square, as on typical modern displays.
How is diagonal resolution found?
Apply the Pythagorean theorem to horizontal and vertical pixels: square both values, add them, then take the square root. Divide that diagonal pixel count by physical diagonal inches.
Why can calculated PPI differ from a specification?
Manufacturers may round the nominal diagonal, and a product listing can describe a family of panels. For installation or calibration, prefer the exact model's technical sheet.
Is PPI the same as CSS pixels?
No. PPI describes physical panel density. CSS pixels are logical units affected by device pixel ratio, operating-system scaling, and browser zoom.
Last reviewed September 22, 2026. Source: W3C CSS Values definition of reference pixels. Product instructions take priority over a general estimate.