Screen PPI Calculator
Calculate a screen's exact pixels-per-inch (PPI), dot pitch, and the viewing distance beyond which individual pixels become imperceptible.
Pixel density
457 PPI
Dot pitch
0.0555 mm
"Retina" distance
7.5 in (19.1 cm)
"Retina" distance is the viewing distance beyond which the average human eye (a resolution limit of about 1 arcminute) can no longer distinguish individual pixels — a real optics calculation, not an Apple-specific spec, though Apple popularized the term. Closer than this distance, individual pixels may become faintly visible; farther away, the display looks equally sharp regardless of PPI.
About this tool
How to use it
- Enter the screen's pixel resolution (width and height in pixels).
- Enter its diagonal size in inches — the number usually quoted for a display (like '6.1-inch screen' or '27-inch monitor').
- Press Calculate PPI, or just keep typing — the results update live.
- Read the pixel density, dot pitch, and the 'retina' viewing distance below.
Why it matters
Pixels per inch (PPI) tells you how sharp a display actually is, independent of its raw resolution — a 4K TV and a 4K phone screen have the same pixel count but wildly different sharpness, because the phone's pixels are packed far more densely into a much smaller physical size. Comparing displays by resolution alone can be misleading; PPI is the number that actually predicts how crisp text and images will look.
When to use it
Useful when comparing two displays with different sizes and resolutions, when choosing a monitor or phone and wondering if a given resolution is 'enough' for its screen size, or when checking a manufacturer's advertised PPI figure against the display's actual specs.
Good to know
'Retina' distance is a genuine optics calculation based on the average human eye's angular resolution limit (roughly 1 arcminute) — Apple popularized the marketing term, but the underlying calculation isn't Apple-specific. Below this distance, individual pixels may become just barely perceptible; beyond it, a higher-PPI display looks no sharper than a lower-PPI one at the same viewing distance, since the eye can no longer resolve the individual pixels either way.
Common questions
What is PPI and why does it matter?
PPI (pixels per inch) measures how densely a screen's pixels are packed — the same pixel resolution stretched over a larger or smaller physical screen results in very different PPI. Higher PPI generally means sharper-looking text and images at a given viewing distance.
What does 'retina' distance actually mean?
It's the viewing distance beyond which the average human eye's angular resolution (about 1 arcminute) can no longer distinguish individual pixels on that specific display. Sit closer than this distance and pixels may become just visible; sit farther and the display looks equally sharp regardless of its actual PPI.
Is a higher PPI always better?
Only up to the point where it exceeds what the eye can resolve at your typical viewing distance — beyond that, more PPI doesn't produce a visibly sharper image, though it can still matter for close-up work or specialized viewing conditions.
What is dot pitch?
Dot pitch is the physical distance between the centers of adjacent pixels, usually expressed in millimeters — it's simply the inverse of PPI converted to metric units, and a smaller dot pitch means more tightly packed, higher-density pixels.