Screen PPI/DPI calculator
Calculate pixels per inch (PPI, sometimes called DPI for a screen) from the resolution and diagonal size of a screen, monitor or phone. Calculated locally in your browser.
How it works
PPI (pixels per inch) measures a screen's display density: the higher the value, the smaller and closer together the individual pixels are, which makes text and images sharper at close range. The calculation uses the Pythagorean theorem to get the diagonal in pixels from the resolution's width and height, then divides it by the physical diagonal in inches.
What is the difference between PPI and DPI?
Technically, PPI refers to the pixel density of a digital screen, while DPI (dots per inch) originally refers to the density of ink dots from a printer. In everyday language, the two terms are often used interchangeably to describe how sharp a display looks.
Does a high PPI always mean better perceived image quality?
Not necessarily: beyond a certain threshold (often around 300 PPI for a smartphone held at normal reading distance), the human eye can no longer easily tell the difference. The PPI you actually need therefore also depends on viewing distance: a billboard viewed from far away can have a very low PPI without looking pixelated.
No data is sent to a server: the calculation stays local, in your browser.