Screen PPI Calculator
Pixels per inch from resolution and diagonal
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Screen PPI Calculator is built for pixels per inch from resolution and diagonal — fast, free, and private. Fill in Width (px), Height (px) and Diagonal (inches) on Screen PPI and read your answer immediately. Screen PPI puts the headline number first. Anyone comparing options in Tech & Digital can use Screen PPI to compare scenarios. Nothing typed into Screen PPI leaves your device or the tab. Looking for ppi calculator pixels per inch screen density resolution diagonal or a quick estimate? Screen PPI covers both. Screen PPI has no learning curve. The fields are labeled. Screen PPI stays bookmarked for next time.
What the defaults give
A 1920 × 1080 panel with a 24-inch diagonal is 91.8 pixels per inch.
PPI measures density, not sharpness. At a desk, 91.8 is fine; the same panel held at phone distance would look coarse, which is why the viewing distance is part of the judgement.
The formula
Diagonal in pixels = √(w² + h²), then PPI = diagonal pixels ÷ diagonal inches.
√(1920² + 1080²) = √(3,686,400 + 1,166,400) = √4,852,800 = 2,202.9 pixels. 2,202.9 ÷ 24 = 91.8 PPI.
Worked example
Resolution 1920 × 1080
Pixel diagonal 2,202.9
Panel diagonal 24 in
PPI = 91.8
What densities suit what
- Phones — 300–500 PPI, because they sit 25–30 cm away.
- Laptops — 150–250 PPI at 40–50 cm.
- Desktop monitors — 90–140 PPI at 60–70 cm; 91.8 is normal for 24 inch 1080p.
- Televisions — 40–80 PPI at 2–3 m, because distance hides the pixels.
Why resolution alone does not decide sharpness
The eye resolves about one arcminute, so what matters is the angular size of a pixel at the distance you sit. A 1080p 24 inch monitor at arm’s length and a 4K 65 inch television at three metres can look equally sharp despite very different PPI — the television’s pixels are further away, not smaller in angle.
Scaling and the practical consequence
High PPI without scaling makes text tiny. Operating systems scale the interface, which is why a 4K 27 inch panel at 163 PPI and 150% scaling gives a usable workspace rather than unusably small text. PPI tells you the potential; scaling decides how it is used.
Frequently Asked Questions
Why is 1080p on 24 inches 91.8 PPI?
The pixel diagonal is √(1920² + 1080²) = 2,202.9 pixels, and 2,202.9 ÷ 24 inches = 91.8 pixels per inch.
Is 91.8 PPI good?
For a desktop monitor at normal viewing distance, yes — it is the standard for 24 inch 1080p. At phone distance the same density would look visibly pixelated.
How do I calculate PPI for any screen?
Take the square root of width² + height² in pixels, then divide by the diagonal in inches. The result is independent of aspect ratio beyond that.
Does higher PPI always look sharper?
Only at the same viewing distance. Sharpness is angular, so a 4K television at three metres can look as sharp as a high-PPI monitor at arm’s length.
What is 4K on a 27 inch monitor?
About 163 PPI — roughly 78% denser than 1080p at 24 inches. That is why those panels ship with 150% interface scaling by default.
How do I work out PPI for a 27 inch 1440p screen?
The pixel diagonal is √(2560² + 1440²) = 2,937 pixels, and 2,937 ÷ 27 = 108.8 PPI. That is denser than 1080p at 24 inches and still needs no scaling, which is why 1440p became the desktop sweet spot.
What is 1080p on a 27 inch screen?
About 81.6 PPI — the same 2,202.9 pixel diagonal over 27 inches. That is low enough that many people see individual pixels in text, which is why 1080p at 27 inches is the panel size most often criticised for sharpness.
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