How it works

PPI (Pixels Per Inch) is calculated by finding the diagonal pixel count using the Pythagorean theorem on your screen's physical resolution, then dividing by the screen's diagonal size in inches. Your physical resolution is determined by multiplying screen.width and screen.height by the devicePixelRatio. Displays with a DPR greater than 1 are considered Retina or HiDPI displays, meaning they pack more physical pixels into each CSS pixel for sharper rendering.