PPI Calculator

Calculate pixels per inch from screen resolution and size.

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How it works

Enter a screen's horizontal and vertical pixel resolution and its diagonal size in inches. The tool finds the diagonal resolution in pixels with the Pythagorean theorem, then divides by the diagonal inches to get pixels per inch (PPI), the measure of pixel density. It also reports the dot pitch in millimetres and the total megapixels. Higher PPI means a sharper display. All math runs locally in your browser.


              PPI = √(w² + h²) / diagonalInches

Common use cases

  • Comparing the sharpness of two monitors or phones.
  • Checking the pixel density of a custom display build.
  • Finding dot pitch for a hardware spec sheet.

Frequently asked questions

Is PPI the same as DPI?

They are often used interchangeably for screens, but strictly PPI (pixels per inch) describes displays while DPI (dots per inch) describes printing. The math here is screen PPI.

What PPI counts as sharp?

It depends on viewing distance, but roughly above 300 PPI is "retina" sharp for phones held close, while monitors look crisp from around 100 PPI and up.

What is dot pitch?

The distance between pixel centres, in millimetres — the inverse of density. A smaller dot pitch means a sharper image.