What is a PPI Calculator?
Resolution alone says nothing about sharpness — 1080p is razor-sharp at 5.5" and coarse at 27". PPI (pixels per inch) is the number that actually compares displays.
Enter resolution and diagonal size to get PPI with a plain-language density class.
How to use the PPI Calculator
- Enter the resolution width and height in pixels.
- Enter the diagonal size in inches.
- Read the PPI and density class.
Frequently asked questions
What is the formula?
PPI = √(width² + height²) ÷ diagonal inches.
What counts as “retina”?
Roughly: pixels invisible at typical viewing distance — ~300+ PPI for phones, ~220 for laptops, ~110 for desktop monitors at arm’s length.
Is higher PPI always better?
Past the invisibility threshold you pay in GPU load and battery for sharpness you cannot see.
Does PPI equal DPI?
PPI is screens; DPI is printer dots. Related concepts, different domains.