Pixel density calculator (screen PPI / DPI)
Calculate a screen's pixels per inch (PPI) from its resolution and diagonal size.
PPI (pixels per inch) measures screen sharpness. Above ~300 PPI the eye no longer sees individual pixels at normal distance ("retina").
How the calculation works
The diagonal in pixels is √(width² + height²) (Pythagoras). PPI is that diagonal divided by the physical diagonal in inches. The dot pitch is the distance between pixels (25.4 mm ÷ PPI).
Examples
- Full HD (1920×1080) on a 24" screen: ~92 PPI.
- The same Full HD on a 5.5" phone: ~400 PPI (much sharper).
Frequently asked questions
Is PPI the same as DPI?
They're used interchangeably for screens, but DPI (dots per inch) is a printing term; PPI is for displays.
How much PPI is "retina"?
It depends on viewing distance: ~300 PPI for phones (close), less for monitors and TVs (farther).
Is more PPI always better?
Up to where the eye can't see pixels. Beyond that, more PPI just costs battery and performance.
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Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources