PPI Calculator — Calculate Pixels Per Inch & Dot Pitch
Compute exact pixel density (PPI), physical dot pitch, aspect ratio, and total screen megapixels for any monitor, laptop, or mobile screen.
Calculate & Calibrate Screen PPI
Standard credit cards and ID cards are exactly 85.60 mm (3.37 inches) wide. Place your real card against your screen over the graphic below, and adjust the slider until both match exactly.
Pixel Density Reference Standards
| Display Type | Resolution | Diagonal | Pixel Density |
|---|---|---|---|
| 24" Standard FHD | 1920 × 1080 | 24.0" | 91.79 PPI |
| 27" Esports QHD | 2560 × 1440 | 27.0" | 108.79 PPI |
| 27" 4K UHD Pro | 3840 × 2160 | 27.0" | 163.18 PPI |
| 32" 4K UHD Desktop | 3840 × 2160 | 32.0" | 137.68 PPI |
| 16.2" MacBook Pro Retina | 3456 × 2234 | 16.2" | 254.00 PPI |
Frequently Asked Questions
What is PPI (Pixels Per Inch)?
PPI measures the pixel density of a screen—the number of individual pixels packed into one linear inch of display surface. Higher PPI yields sharper text, clearer curves, and less noticeable pixelation.
What is the mathematical formula for PPI?
PPI is calculated using the Pythagorean theorem: PPI = sqrt(Width² + Height²) ÷ Diagonal Inches.
What is a good PPI for desktop monitors vs smartphones?
Standard desktop viewing distance (24–36 inches) is comfortable at 90–110 PPI (1080p 24" or 1440p 27") and exceptionally sharp at 140–160+ PPI (4K 27–32"). Smartphones held 10–12 inches away typically target 350–460+ PPI.
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