Pixel Density PPI Calculator
Pixel Density PPI
Calculate pixels per inch (PPI) for displays and prints to determine sharpness and optimal viewing distance for photography.
Formula
PPI = sqrt(Width^2 + Height^2) / Diagonal Size; Optimal Viewing Distance = 3438 / PPI (in inches); Dot Pitch = 25.4 / PPI (in mm)
Frequently Asked Questions
What PPI is considered 'retina' quality?
Apple defines retina as when pixels are indistinguishable at normal viewing distance — roughly 220+ PPI for phones held at 10 inches, and 110+ PPI for monitors at 20 inches.
What PPI should I use for photo prints?
300 PPI is the standard for high-quality photo prints. 150 PPI is acceptable for large prints viewed from a distance. Billboards can use 10-30 PPI.
Does higher PPI always mean better?
Above a certain PPI, the human eye cannot distinguish individual pixels. For desktop monitors at typical viewing distance, 110-140 PPI is standard and 200+ is excellent.
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