Screen PPI Calculator

PPI for this display using CSS size, device pixel ratio, and a diagonal you type.

CSS pixels are multiplied by this screen’s device pixel ratio (—). That is how this browser reports the display, not a calibrated meter. Enter the physical diagonal yourself — the browser does not know it.

CSS width

px

CSS height

px

Diagonal

in

PPI

—

Worked example

CSS pixels are multiplied by this screen’s device pixel ratio before the diagonal is applied. A ratio of 2 turns 1512 CSS pixels of width into 3,024 device pixels.

FAQ

Why multiply by the device pixel ratio?: CSS pixels aren't always physical pixels. On a retina-style screen one CSS pixel is two or more device pixels.
What should I enter for the diagonal?: The physical screen size in inches. The browser does not know it.
Will two laptops with the same CSS size match?: Only if the pixel ratio and the physical diagonal match.