Screen PPI calculator
Resolution alone says nothing about sharpness — 4K on a 27-inch monitor and on a 65-inch television are very different things. Pixel density is the figure that matters, along with the distance at which it stops mattering.
- Aspect ratio
- 16:9
- Megapixels
- 3.69
- Physical width, cm
- 59.8
- Physical height, cm
- 33.6
- Dot pitch, mm
- 0.2335
- Pixels invisible beyond, cm
- 80
- Screen area, cm²
- 2,010
The formula
Diagonal pixels = √(width² + height²), and PPI = diagonal pixels / diagonal inches. The physical width and height follow by proportion. The distance at which individual pixels stop resolving is about 3438 / PPI inches, from the one-arcminute limit of normal acuity.
Worked example
2560 × 1440 on 27 inches gives 108.8 PPI, a 16:9 ratio, a screen 59.7 cm wide, and pixels that stop being distinguishable beyond about 80 cm.
How to use it
- 1Use the native resolution, not the one you have set.
- 2Screen sizes are quoted as the diagonal of the panel, excluding the bezel.
- 3Compare the viewing-distance figure against where you actually sit. Beyond it, more pixels are wasted.
Questions people ask
How much PPI do I need?
It depends on distance. A phone at 25 cm wants 300 or more; a desktop monitor at 60 cm is comfortable around 110 to 160; a television across a room is fine at 40. Density and distance trade off directly.
Is a 4K television sharper than a 4K monitor?
No, it is far less dense — the same pixels spread over a much larger panel. It only looks comparable because you sit several times further away.
Last reviewed: 2026-10-20