PPI Calculator
Find the pixel density of any display from its resolution and diagonal size. Shows PPI, total pixels, megapixels and a sharpness verdict.
How pixel density is calculated
Pixels per inch measures how tightly packed a display's pixels are. Because a screen's advertised size is its diagonal, the calculation uses the diagonal pixel count from the Pythagorean theorem:
PPI = √(width² + height²) ÷ diagonal inches
A 27-inch 2560×1440 monitor has a diagonal of √(2560² + 1440²) ≈ 2937 pixels, which over 27 inches gives about 109 PPI. The reciprocal is the dot pitch — the physical width of one pixel, here about 0.233 mm. Smaller dot pitch means a sharper image.
Why the same resolution looks different on different screens
Resolution alone tells you nothing about sharpness. A 24-inch and a 32-inch 1080p monitor have exactly the same number of pixels, but the 32-inch spreads them over a much larger area: 92 PPI versus 69 PPI. That is why a large, low-resolution monitor looks grainy while a laptop screen with fewer total pixels can look razor sharp.
Common desktop densities
| Panel | Density | In practice |
|---|---|---|
| 24" 1080p | 91.8 PPI | The most common office monitor. Text is a little soft up close. |
| 27" 1080p | 81.6 PPI | Same pixels stretched wider - noticeably grainy on a desk. |
| 27" 1440p | 108.8 PPI | The desktop sweet spot: sharp at 100% scaling. |
| 32" 1440p | 91.8 PPI | Identical density to a 24" 1080p panel, just bigger. |
| 27" 4K | 163.2 PPI | Very sharp, but needs 150% scaling to be readable. |
| 32" 4K | 137.7 PPI | Sharp and usable at 125% scaling - a popular creator choice. |
Density and display scaling
Windows and macOS assume roughly 96–110 effective PPI for unscaled interfaces. Much above that and menus and text become too small, which is why a 27-inch 4K panel needs 150% scaling to be comfortable. The scaling suggestion above targets that comfortable effective density.
How close is too close?
Human vision resolves detail down to about one arc-minute. Beyond that distance, individual pixels blend together regardless of density — the calculator reports where that point falls for your panel. If you want the reverse answer, how far to sit from a given screen, use the Viewing Distance calculator.
Frequently asked questions
What is a good PPI for a monitor?
Around 110 PPI is the desktop sweet spot - sharp text at 100% scaling with no fiddling. A 27-inch 1440p panel hits this almost exactly. Below 90 PPI text starts to look soft; above about 150 PPI you will want display scaling.
Is 4K worth it on a 27-inch monitor?
It gives a very sharp 163 PPI, but you will need 150% scaling, so you gain clarity rather than desktop space. For more usable area at a comfortable density, a 32-inch 4K panel (138 PPI) is usually the better choice.
Why does my 32-inch 1080p monitor look blurry?
At 32 inches, 1080p works out to just 69 PPI - among the lowest densities still sold. Individual pixels are visible at desk distance. Either sit further back or move to 1440p or 4K at that size.
Does higher PPI need a more powerful graphics card?
Density itself costs nothing, but it usually comes with more pixels to render. Going from 1440p to 4K is 2.25 times the pixels and a large GPU load increase. Check yours with the FPS Calculator.
Is PPI the same as DPI?
They are used interchangeably but strictly PPI describes screen pixels and DPI describes printed dots. For displays, PPI is the correct term.