Monitor PPI and pixel-density calculator
Screen size alone does not describe how finely pixels are packed. Combine the native resolution with the diagonal measurement to calculate PPI, approximate pixel pitch and the physical width and height of the visible panel.
Enter the display specifications
Calculation result
- Pixel density
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- Pixel pitch
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- Physical panel area
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- Aspect ratio
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- Approximate angular threshold
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Compare two display sizes side by side (24″ vs 27″ vs 34″ Ultrawide)
Diagonal size alone can be misleading when comparing different aspect ratios. For example, a 34-inch 21:9 ultrawide monitor has nearly the same vertical height as a 27-inch 16:9 display. Use the interactive comparator below to visualize physical dimensions, screen area, and PPI differences to scale.
| Metric | Display A | Display B |
|---|---|---|
| Physical width × height | — | — |
| Pixel density (PPI & pitch) | — | — |
| Total panel area & megapixels | — | — |
Display reported to the browser
Reading information…
Operating-system scaling, browser zoom and multi-monitor setups can change these values. Do not treat them as a definitive hardware specification.
What does PPI mean?
PPI is the number of pixels placed along one inch of the display. The same resolution on a smaller panel produces a higher density. A 27-inch 2560×1440 monitor is roughly 109 PPI, while a 27-inch 3840×2160 panel is roughly 163 PPI. Pixel density does not measure contrast, color accuracy, response time or overall panel quality.
PPI = √(horizontal pixels² + vertical pixels²) ÷ diagonal inches
Pixel pitch = 25.4 mm ÷ PPI
Common desktop combinations
| Size and resolution | Approximate PPI | Practical context |
|---|---|---|
| 24″ 1920×1080 | 92 | A common desktop density; the pixel structure can be easier to notice at short distances. |
| 27″ 2560×1440 | 109 | A frequently chosen balance between workspace and readable interface size. |
| 27″ 3840×2160 | 163 | Fine text and lines benefit from the density, while interface scaling is commonly used. |
| 32″ 3840×2160 | 138 | Provides a larger physical presentation of a 4K workspace. |
How should the angular threshold be interpreted?
The distance shown by the calculator is the geometric point where one pixel spans approximately one arcminute. It is not a health recommendation, a mandatory viewing distance or a vision test. Individual eyesight, subpixel layout, antialiasing, scaling and content all influence whether pixels are visible. Use the number as a consistent comparison between displays rather than an “ideal” distance.
Using PPI in a buying decision
- Decide how much workspace you need. Resolution can increase usable space, but operating-system scaling changes how much content is actually visible.
- Consider your normal viewing distance. A small close-up display and a large distant display can feel different at the same PPI.
- Account for scaling support. Scaling enlarges interface elements; it does not change the panel's physical PPI.
- Test panel quality separately. PPI says nothing about dead pixels, backlight uniformity, ghosting or color accuracy. Use the monitor test guide for those checks.
Frequently asked questions
Is a higher PPI always better?
It can improve perceived sharpness, but graphics performance, scaling support, panel quality, price and viewing distance also matter.
Can the browser detect my physical screen size?
Usually not reliably. A browser can report CSS dimensions and a device-pixel ratio, but it does not normally expose a trustworthy physical diagonal.
Can I use centimetres?
Divide the diagonal in centimetres by 2.54 before entering it. For example, 68.6 cm is approximately 27 inches.
Does the formula work for ultrawide monitors?
Yes. Enter the actual diagonal and native horizontal and vertical resolution; the same geometry works for 21:9 and 32:9 panels.