How PPI is Calculated
Diagonal Pixels = √(Width² + Height²)
PPI = Diagonal Pixels ÷ Diagonal Inches
Frequently Asked Questions
What PPI is considered "Retina"? Apple considers a display "Retina" when pixels aren't individually visible at typical viewing distance — roughly 220+ PPI for phones, 200+ for tablets, and 100+ for monitors.
Is higher PPI always better? Higher PPI means sharper text and images, but beyond a certain point the human eye can't distinguish the difference at normal viewing distances.