PPI Density Calculator
Find a screen's pixels-per-inch and dot pitch.
How to use
- 1 Enter the horizontal and vertical resolution in pixels.
- 2 Enter the diagonal screen size and choose inches or centimetres.
- 3 Read the PPI, density class, megapixels and aspect ratio.
- 4 Copy the summary for your notes or comparison.
About PPI Density Calculator
The PPI Density Calculator works out how sharp a display really is.
Enter the screen resolution in pixels and its physical diagonal size, and it computes the pixel density in pixels per inch (PPI) — the figure that tells you whether individual pixels will be visible or blend into a crisp, continuous image.
From the same inputs it derives a whole panel profile: pixels per centimetre for metric workflows, the dot pitch (the distance in millimetres between neighbouring pixel centres), the total pixel count and its megapixel equivalent, the simplified aspect ratio such as 16:9 or 8:5, and a rough density class from Low through Standard and High up to Retina-class.
The diagonal can be entered in inches or centimetres, so it works equally well for monitors, laptops, phones, tablets and TVs from any spec sheet.
The maths is straightforward but easy to get wrong by hand: the diagonal resolution is found with Pythagoras from the width and height, then divided by the physical diagonal to give PPI.
This tool does it instantly and accurately.
Everything is calculated locally in your browser with no uploads or tracking, so it stays fast and private and works offline.
Use it to compare displays before buying, to check whether a panel is "retina" at your viewing distance, or to plan UI and asset resolutions for a target device.
FAQ
How is PPI calculated?
The diagonal in pixels is found with Pythagoras from the width and height, then divided by the physical diagonal in inches: PPI = √(width² + height²) / diagonal.
What counts as a "retina" or high-density display?
It depends on viewing distance, but as a rough guide this tool labels under 120 PPI as Low, 120–200 as Standard, 200–300 as High, and 300+ as Retina-class, where pixels are typically indistinguishable at normal distances.
What is dot pitch?
Dot pitch is the distance between the centres of adjacent pixels, shown here in millimetres. A smaller dot pitch means a denser, sharper screen.