Find the pixel density, dot pitch and sharpness class of any screen from its resolution and diagonal — in your browser.
PPI (pixels per inch) measures how densely a display packs its pixels, and it is the number that actually determines how sharp a screen looks — resolution alone does not. A 1920×1080 panel is razor-sharp at 5 inches on a phone and visibly coarse at 27 inches on a desk. This calculator applies the Pythagorean theorem to the resolution to get the diagonal in pixels, divides by the physical diagonal in inches, and reports the resulting density along with the dot pitch (the physical distance between pixel centers, in millimeters) and the total pixel count in megapixels.
To make the number meaningful, the result is placed in a density class with real-world reference points: around 92 PPI is the classic 24-inch 1080p office monitor, about 109 PPI is a 27-inch 1440p display, 163 PPI is a 27-inch 4K panel, 220–260 PPI is the territory of premium laptop screens, and modern smartphones run from roughly 400 to over 500 PPI. As a rule of thumb, higher density stops being perceptible once pixels are smaller than your eye can resolve at the typical viewing distance — which is why a phone needs far more PPI than a TV to look equally sharp.
Concrete uses: comparing two monitors before buying (a 27-inch 1440p and a 24-inch 1080p differ more than the spec sheets suggest), checking whether a 4K upgrade will be noticeable at your desk, estimating how large a screen can get before a given resolution turns grainy, or picking assets and scaling factors when designing for a specific device. The presets cover the common 16:9 resolutions from Full HD to 8K so you only have to type the diagonal. Everything is computed 100% in your browser — nothing is sent anywhere.
PPI = √(width² + height²) ÷ diagonal in inches. Dot pitch (mm) = 25.4 ÷ PPI. Example: 1920×1080 at 24 inches → √(1920² + 1080²) ÷ 24 ≈ 91.8 PPI.
Around 90–110 PPI is the comfortable standard for desktop work, 140–170 PPI (for example, 27-inch 4K) looks noticeably sharper, and above that most people cannot see individual pixels at desk distance. For laptops, 150–260 PPI is typical; phones go much higher because they are held closer.
PPI counts pixels per inch on a display; DPI counts ink dots per inch on a printer. In everyday language the terms are used interchangeably for screens, and the math in this calculator is the same either way.
The physical distance between the centers of two adjacent pixels, in millimeters — simply 25.4 divided by the PPI. A smaller dot pitch means a denser, sharper image; a 92 PPI monitor has a dot pitch of about 0.28 mm.
Only up to the limit of your eyes at a given distance. Sharpness perception depends on PPI and viewing distance together: a 55-inch 4K TV has just 80 PPI yet looks sharp from a couch, while a phone needs 400+ PPI at arm length.
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