Screen PPI and Dot Pitch Calculator
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Work out a screen's pixel density. PPI is how many pixels fit in one inch, and it is the measure that actually answers "how small are the pixels" — far more useful than the resolution on its own. The same 1920×1080 is 92 PPI on a 24-inch monitor and 147 PPI on a 15-inch laptop, and they look nothing alike. Marketing terms like "2K", "4K" and "retina" all describe resolution, which has no direct bearing on sharpness. The calculation is just Pythagoras: the diagonal in pixels divided by the diagonal in inches. Alongside PPI this also reports dot pitch in millimetres, which is the same fact said differently.
Features
- Pixel density in PPI, plus dot pitch in millimetres
- Aspect ratio written the conventional way (16:9, 16:10) and the total pixel count
- A plain-language verdict, with the bands drawn from screens people actually buy
- A zero or negative diagonal yields no result rather than Infinity
- Zero or negative pixel counts are treated as 1 instead of producing a row of NaNs
How to use
- Enter the resolution width and height (say 1920 × 1080)
- Enter the screen diagonal in inches, as listed on the product page
- Results appear as you type — no Run button needed
- Copy individual rows if you need them
FAQ
- Does a higher resolution mean a sharper picture?
- No. Sharpness depends on density, which depends on the resolution and the screen size together. The same 1920×1080 is 92 PPI on a 24-inch monitor and 147 PPI on a 15-inch laptop — clearly finer on the laptop, even though the "resolution" in the spec sheet is identical. Conversely a 32-inch 4K display (138 PPI) is less dense than a 27-inch 4K (163 PPI). Both numbers have to be read together to mean anything.
- How much PPI is enough?
- It depends on viewing distance. A desktop monitor at 50–70 cm looks smooth at 110–160 PPI; a laptop sits closer, so 200 PPI and up is where "retina" territory begins; phones are used within about 25 cm and mainstream models are all above 400 PPI. That is why 300 PPI is unremarkable on a phone but exceptional on a monitor — what counts as dense is relative to distance.
- Are dot pitch and PPI the same thing?
- They are two ways of saying it. Dot pitch is the distance between adjacent pixel centres in millimetres; PPI is the number of pixels per inch. Each is the reciprocal of the other: `dot pitch (mm) = 25.4 ÷ PPI`. Hardware reviews tend to quote dot pitch ("a 0.27 mm pitch panel"), while English-language sources quote PPI. Smaller pitch and larger PPI both mean denser pixels.
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