Last updated: March 2, 2026

How to Calculate Pixel Density (PPI)

Formula

PPI measures how tightly pixels are packed on a display. Higher PPI means sharper images.

The formula divides the diagonal pixel count by the physical diagonal size in inches.

Common use cases:

  • Comparing display sharpness across devices
  • Determining Retina-quality thresholds
  • Print resolution planning

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