PPI vs DPI — What's the Difference?
Both abbreviate to "dots/pixels per inch," but they describe different things.
PPI — Pixels Per Inch
Used for screens and digital displays. It's how many device pixels fit in one inch of the panel. Higher PPI = sharper display.
DPI — Dots Per Inch
Used for printers and physical output. It's how many ink dots a printer lays down per inch. Higher DPI = finer print.
Why the confusion?
Software sometimes reports a "DPI" setting for screens (e.g. 96 DPI UI scaling), but that's a legacy misnomer — it's really about logical pixel density, not physical ink. When people ask for a "PPI calculator," they mean screen pixel density, not print resolution.
Calculate your screen's PPI
PPI Calculator
√(W²+H²) ÷ size — precise to 0.1 PPIUnit:
in
Use the diagonal printed on the box or spec sheet.
in wide
For when you measured the viewable width with a ruler.
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PPI
—PPI = √(W² + H²) ÷ diagonal · Retina-class estimate ≥ 300 PPI (approximate; depends on viewing distance)