PPI / Pixel Density Calculator
Pixels per inch and dot pitch from a screen resolution and diagonal size.
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Step by step
The formula
PPI = √(w² + h²) ÷ diagonal
Pixel density describes how tightly packed a display’s pixels are, which decides whether you can see them individually. It depends on resolution and physical size together — the same 1920×1080 is crisp on a phone and visibly coarse on a television.
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Common questions this calculator answers — select one to load its values.
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Frequently asked questions
What PPI counts as "retina"?+
There is no fixed number, because it depends on viewing distance. Roughly 300 PPI for a phone held close, about 220 for a laptop and around 150 for a desktop monitor at arm’s length.
Is higher PPI always better?+
Only up to the point where you can no longer distinguish pixels. Past that it consumes more graphics power and battery for no visible gain, which is why televisions viewed from a sofa have far lower PPI than phones.
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