PPI Calculator

Calculate pixel density (PPI) and dot pitch from screen diagonal size and resolution.

Category: Calculators

When to use?

Use it before buying a monitor or phone to compare sharpness — for example, how FHD and QHD differ on the same 27 inches. It also helps compare pixel density for design/video monitors or review phone screen specs.

How to use

  • Enter the screen diagonal size in inches.
  • Enter the horizontal and vertical resolution (pixels).
  • PPI, dot pitch, actual screen size, and aspect ratio are calculated automatically.

Input Explanation

Enter the diagonal in inches from the spec sheet (e.g. 27"), and the resolution in pixels (e.g. 2560 × 1440). Preset buttons fill in common monitor/phone specs.

Calculation Basis

PPI = √(width² + height²) ÷ diagonal inches. Dot pitch (pixel spacing) = 25.4 ÷ PPI (mm); actual screen size = resolution ÷ PPI.

Usage Examples

  • Compare monitor sharpness - Compare PPI of same-inch monitors with different resolutions to pick the sharper one.
  • Check phone screen specs - Find the pixel density from a phone's screen size and resolution.
  • Review a work display - Use dot pitch to check whether it meets the pixel density needed for design/photo work.

Examples

  • 27" QHD (2560×1440) → about 108.8 PPI
  • 6.1" FHD+ (1170×2532) → about 460 PPI

Cautions

  • The result does not account for the physical display's subpixel arrangement.
  • Subpixel layouts (e.g. Pentile) can make perceived sharpness differ from the calculated value.

Guides

PPI formula

PPI = √(width pixels² + height pixels²) ÷ diagonal inches. At the same screen size, a higher resolution gives a higher PPI and more sharpness.

PPI and viewing distance

A higher PPI means denser pixels. But monitors and TVs viewed from a distance look sharp enough even at low PPI, so judge by use case.

FAQ

How is PPI calculated?

Find the diagonal pixel count from width and height (√(w²+h²)), then divide by the diagonal in inches.

Are PPI and DPI the same?

PPI is pixels per inch on a screen; DPI is dots per inch in print. They are used loosely as synonyms, but screen sharpness is more accurately PPI.

Is higher PPI always better?

Higher PPI means denser pixels and more sharpness, though perceived sharpness also depends on viewing distance.

What does dot pitch mean?

The spacing of one pixel (mm); a smaller value means denser pixels and a sharper screen.

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