Sharpness Is Density, Not Resolution

A 4K screen on a phone and a 4K screen on a 65\" TV have identical pixel counts but wildly different sharpness. This pixel density calculator computes the PPI — resolution spread over physical size — which is the number that actually determines perceived crispness.

One Formula, Three Answers

Diagonal resolution divided by diagonal size gives PPI; its reciprocal is the dot pitch in inches, which is easier to think about in millimeters. The calculator also derives the physical width and height of the panel, so you can picture exactly how big that 27\" really is.

Buying With PPI in Mind

Before buying, check the PPI at your intended viewing distance. Desktop monitors around 110 PPI (1080p at 24\") are fine; 1440p at 27\" (~109 PPI) is the sweet spot for most; and 4K at 27\" (~163 PPI) starts to approach the limit of what eyes can resolve.