Monitor PPI Calculator
Calculate pixels per inch for any monitor or screen. Enter diagonal size and resolution to get PPI, dot pitch, physical dimensions, and sharpness rating.
Enter diagonal size and resolution to calculate PPI.
Monitor PPI Calculator: What Is Pixels Per Inch?
Pixels Per Inch (PPI) measures the pixel density of a display: how many individual pixels are packed into each inch of screen space. A higher PPI means sharper text, crisper images, and finer detail. The formula uses the Pythagorean theorem applied to the resolution and physical diagonal size: PPI equals the square root of (width squared plus height squared) divided by the diagonal in inches. This calculator also shows dot pitch, physical dimensions, total pixel count and aspect ratio.
Dot Pitch (mm) = 25.4 / PPI
Pixels/cm = PPI / 2.54
Example: 27" 2560×1440
sqrt(2560² + 1440²) = 2937.2 px diagonal
2937.2 / 27 = 108.79 PPI
Dot pitch = 25.4 / 108.79 = 0.2335 mm
PPI Sharpness Scale
The sharpness class is this calculator's own set of bands, not an industry standard: below 50 PPI is Very Low, 50 to 72 Low (TV Distance), 72 to 100 Standard, 100 to 140 Sharp (Desktop), 140 to 220 High Definition, and 220 or more Retina / HiDPI. Treat it as a quick label; whether a screen looks sharp also depends on how far away you sit.
Example Monitor Combinations
A 27-inch screen at 2560x1440 (QHD) has 109 PPI. A 24-inch Full HD monitor reaches 92 PPI, while the same 27-inch panel at Full HD drops to 82 PPI. A 27-inch 4K panel gives 163 PPI, and a 32-inch 4K monitor 138 PPI.
PPI and Viewing Distance
With 20/20 vision the eye separates details about one arcminute apart, which works out to 60 pixels per degree of visual angle. At 60 cm from the screen that limit is about 146 PPI: below it, a sharp eye can in principle pick out single pixels. At 2 meters it falls to about 44 PPI, which is why an 80 PPI 4K television looks smooth from the couch while the same density on a desk monitor shows its pixels. For desk monitors, OSHA's workstation guidance gives a viewing distance of 50 to 100 cm (20 to 40 inches).
Dot Pitch Explained
Dot pitch is the physical distance in millimeters between the centers of two adjacent pixels. It is simply 25.4 divided by PPI. A 27-inch QHD monitor has a dot pitch of 0.233 mm, while the same size at Full HD has 0.311 mm.
Tips & Recommendations
At 27", moving from Full HD to QHD raises the density from 82 to 109 PPI.
4K gives 163 PPI at 27", 138 PPI at 32" and 80 PPI at 55": the same pixels spread over a larger panel.
Dot pitch is 25.4 divided by PPI, so 0.25 mm corresponds to 101.6 PPI.
OSHA's workstation guidance puts a desk monitor 50 to 100 cm (20 to 40 inches) from the eyes.
Frequently Asked Questions
What is PPI on a monitor?
PPI stands for Pixels Per Inch. It measures how many pixels fit into one inch of screen space. A 27-inch monitor at 2560x1440 has about 109 PPI, while the same monitor at 1920x1080 has only 82 PPI. Higher PPI means sharper, more detailed images.
What PPI is considered sharp for a desktop monitor?
This calculator calls 100 to 140 PPI Sharp (Desktop), 140 to 220 High Definition and 220 or more Retina / HiDPI. These are the tool's own labels; whether you can see single pixels depends on viewing distance (at 60 cm the 20/20 limit is about 146 PPI).
Does PPI matter more than resolution?
Both matter together. A 4K 55-inch TV has 80 PPI, while a 4K 27-inch monitor has 163 PPI. The TV uses the same resolution but at greater viewing distance, so the lower PPI is acceptable. Resolution, screen size and viewing distance together decide how sharp a screen looks.
What is dot pitch?
Dot pitch is the physical distance in millimeters between the centers of adjacent pixels. It is the inverse of pixel density: a 27-inch QHD monitor has a dot pitch of about 0.233 mm, while a 27-inch FHD monitor has about 0.311 mm. Smaller dot pitch means tighter pixels and a sharper image.
Which monitor size and resolution combination gives 100+ PPI?
27 inches at 2560x1440 (109 PPI), 24 inches at 2560x1440 (122 PPI), 32 inches at 3840x2160 (138 PPI) and 15.6-inch laptops at 1920x1080 (141 PPI) are all above 100 PPI. A 24-inch Full HD monitor stays below, at 92 PPI.
How does viewing distance relate to PPI?
The further you sit from a screen, the less PPI you need to perceive a sharp image. A 55-inch TV at 80 PPI looks sharp from 2 to 3 meters, while a desktop monitor at the same PPI would show its pixels at 60 cm. The 60 pixels per degree limit of 20/20 vision is about 146 PPI at 60 cm and about 44 PPI at 2 meters.
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