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PPI Calculator (Pixel Density)

Enter any resolution and diagonal screen size to get PPI, total pixels, aspect ratio, dot pitch, and the viewing distance beyond which individual pixels disappear.

Tool not available.

Common Display Densities

Device classTypical resolutionSizePPI
Office monitor1920×108024"92
Pro monitor3840×216027"163
Laptop2880×180015.4"221
Flagship phone1170×25326.1"457
Tablet2048×273212.9"264

How the Estimate Is Built

  1. Enter the screen resolution (width and height in pixels) and the diagonal size in inches.
  2. The tool computes PPI from the diagonal pixel count and the diagonal in inches.
  3. Total pixels, aspect ratio, and dot pitch (the size of one pixel in mm) are reported alongside.
  4. Viewing-distance guidance derives from 20/20 visual acuity: roughly 1.5× PPI in centimeters.
Formula & Technical Standard
PPI = √(W² + H²) ÷ diagonal · dot pitch = 25.4/PPI mm · acuity distance (cm) ≈ 5730/PPI × 1.5 (Apple Retina convention).

Worked Example

Desktop monitor
Input: 1920×1080 at 24 inches
Output: 91.8 PPI · 0.28 mm dot pitch
The standard office display density; text is comfortable at 60+ cm, and individual pixels become invisible beyond roughly 94 cm.
Smartphone
Input: 1170×2532 at 6.1 inches
Output: 457 PPI
Held at 25 cm, a phone needs ~340+ PPI for pixels to vanish — which is why flagship phones cluster around 450–500.

Common Questions

Is PPI the same as DPI?

Strictly no: DPI (dots per inch) describes printer dot density, while PPI describes screen pixels. In practice the terms are used interchangeably for displays, and this calculator reports PPI for screens.

What PPI do I need for a monitor?

It depends on distance and task. 24-inch 1080p (92 PPI) is the office baseline; 27-inch 4K (163 PPI) renders near-print sharpness at desk distance; below ~80 PPI individual pixels become noticeable during text work.

How is the Retina viewing distance calculated?

It inverts the acuity limit of one arc-minute per pixel for 20/20 vision: distance (cm) ≈ 5730 × 1.5 / PPI. Sitting farther than that, adjacent pixels cannot be resolved separately.

Does PPI affect perceived screen size of UI?

Yes, which is why operating systems scale the interface. Higher PPI at the same physical size means smaller raw UI elements, so macOS/Windows/Android apply scaling factors to keep things usable.

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