PPI Calculator
Work out the pixel density of any screen from its resolution and diagonal size. Returns pixels per inch, dot pitch, aspect ratio, and total megapixels.
Standard density — typical of most desktop monitors.
Pixel density of common displays
Every value below is calculated with the same formula this tool uses.
| Display | Resolution | PPI |
|---|---|---|
| 1080p · 24" | 1920 × 1080 | 91.8 |
| 1080p · 27" | 1920 × 1080 | 81.6 |
| 1440p · 27" | 2560 × 1440 | 108.8 |
| 1440p · 32" | 2560 × 1440 | 91.8 |
| 4K · 27" | 3840 × 2160 | 163.2 |
| 4K · 32" | 3840 × 2160 | 137.7 |
| 4K · 55" | 3840 × 2160 | 80.1 |
| 1600p · 13.3" | 2560 × 1600 | 227.0 |
Know exactly how sharp a screen is
Screen size and resolution only mean something together. A 4K panel is razor sharp at 27 inches and merely average at 55. Pixels per inch is the number that settles it.
The formula
The square root gives you the diagonal length in pixels. Dividing by the physical diagonal in inches turns that into pixels per inch.
How this PPI Calculator works
This calculator works out the pixel density of any display from two things: its resolution in pixels and its diagonal size in inches. It first uses the Pythagorean theorem on the horizontal and vertical pixel counts to find how many pixels lie along the diagonal, then divides that by the physical diagonal length. The result is pixels per inch, the standard measure of how sharp a screen is.
Pixel density matters because neither resolution nor screen size means much on its own. A 4K panel sounds impressive until you spread those pixels across a 55-inch television, at which point the density drops to roughly 80 PPI — lower than an ordinary 24-inch 1080p monitor. The same panel at 27 inches reaches about 163 PPI and looks dramatically crisper. Viewing distance is the other half of the picture: phones need very high densities because you hold them close, while a television across the room can get away with far less.
Alongside PPI the tool reports three related figures. Dot pitch is the distance between neighbouring pixel centres in millimetres, which is simply the inverse of density. Aspect ratio is the width-to-height relationship reduced to its simplest whole numbers, so 2560 by 1440 shows as 16:9. Total pixels is the raw count, given in megapixels, which is a rough proxy for how much work a GPU has to do to drive the display.
Everything is calculated in your browser as you type, and nothing you enter is sent to a server.
How to use this PPI Calculator
Enter the resolution
Type the horizontal and vertical pixel counts, for example 2560 by 1440.
Enter the diagonal
Add the screen size in inches — the figure manufacturers advertise, measured corner to corner.
Read the density
PPI updates instantly, along with dot pitch, aspect ratio, and total pixels.
Example Usage
A standard 1440p desktop monitor:
Frequently Asked Questions
What is PPI?
How is PPI calculated?
Is PPI the same as DPI?
What is a good PPI for a monitor?
Why do two screens with the same resolution look different?
What is dot pitch?
Does a higher PPI always look better?
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The PPI Calculator is maintained by CodeItBro. We aim to provide the best free developer tools on the web. If you have feedback or suggestions, please visit our contact page.
