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Screen PPI Calculator

Work out the pixel density of a phone, laptop, monitor or TV from its resolution and diagonal size, plus its width and height, dot pitch and the distance where pixels disappear.

Rules last checked 25 October 2026Every step shown

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px
inches

Pixel density

91.8 PPI

Dot pitch (pixel size)
0.277 mm
Screen width × height
20.9 × 11.8 in (53.1 × 29.9 cm)
Aspect ratio
16:9
Total pixels
2.07 megapixels
Pixels blend together beyond
37.5 in (95 cm)

A 24-inch 1,920 × 1,080 screen has 91.8 pixels per inch; with normal eyesight the pixels disappear beyond about 95 cm.

How it's worked out

  1. Diagonal in pixels√(1,920² + 1,080²)2,202.91 px
  2. PPI2,202.91 ÷ 24 in91.79
  • The blending distance assumes 20/20 vision, which resolves about one arcminute.

The formula

PPI = √(w² + h²) ÷ diagonal · Dot pitch (mm) = 25.4 ÷ PPI

Example

A 24-inch 1920 × 1080 monitor has a diagonal of 2,202.9 pixels, so 91.8 PPI and a dot pitch of 0.277 mm. The screen is 20.9 × 11.8 inches (53.1 × 29.9 cm), and with normal eyesight the pixels blend together beyond about 95 cm.

Questions people ask

How is PPI calculated?

Divide the diagonal resolution in pixels by the diagonal size in inches: PPI = √(width² + height²) ÷ diagonal.

What is a good PPI?

Around 90 to 110 PPI is normal for desktop monitors viewed at arm's length. Phones are 400 or more because you hold them close.

What PPI is a 27-inch 1440p monitor?

About 108.8 PPI, compared with 91.8 for a 24-inch 1080p monitor.

Is PPI the same as DPI?

They are often used the same way for screens. Strictly, DPI is for printers (dots of ink) and PPI for screens (pixels).

Formula and rules last checked 25 October 2026Written and tested by the CalculatorDex teamReport a problem