How is PPI calculated?

PPI = √(width² + height²) ÷ diagonal-in-inches. For a 2560×1440 screen on a 27-inch panel that is √(2560² + 1440²) ÷ 27 ≈ 108.8 PPI.

What is the difference between DPI and PPI?

PPI (pixels per inch) describes screen pixel density, while DPI (dots per inch) describes printer dot density. For displays the terms are used interchangeably, and this tool computes pixels per inch.

Dot pitch is the distance between the centres of neighbouring pixels, equal to 25.4 ÷ PPI millimetres. A smaller dot pitch means a sharper image.

DPI / PPI Calculator

Pixel density from resolution and diagonal screen size.

DPI / PPI calculator

Work out the pixel density of any monitor, phone or tablet from its resolution and diagonal size. The tool returns PPI, the dot pitch in millimetres, and the active display area in inches and centimetres.

PPI is computed as √(width² + height²) ÷ diagonal-in-inches — the same formula used to compare screen sharpness. Everything runs in your browser.