Screen PPI Calculator
Enter a resolution and diagonal size to see pixel density, and how far away you can sit before individual pixels become invisible.
Pixel density–
–Dot pitch
–Pixels blend beyond
–Screen width × height
What PPI means in practice
PPI (pixels per inch) is the diagonal pixel count divided by the diagonal size. Higher PPI means sharper text at the same distance. The "pixels blend" distance uses the common rule that a person with 20/20 vision resolves about one arcminute; beyond that distance, more pixels add little visible sharpness.
That is why a 65-inch 4K TV looks sharp from the sofa but would look soft as a desk monitor, while a phone needs very high PPI because it sits 30 cm from your eyes.