Pixel Density Calculator – Calculate PPI and Display Metrics
Calculate PPI and display metrics from resolution and screen size
How to Use
- Enter the horizontal resolution in pixels (e.g., 1920)
- Enter the vertical resolution in pixels (e.g., 1080)
- Enter the diagonal screen size
- Select the unit (inches or centimeters)
- Click calculate to see PPI and other display metrics
What is Pixel Density (PPI)?
Pixel density, measured in pixels per inch (PPI), indicates how many pixels are packed into one inch of screen space. Higher PPI means sharper images and text because individual pixels are smaller and less visible to the naked eye.
PPI is calculated by dividing the diagonal resolution (in pixels) by the diagonal screen size (in inches). The diagonal resolution is found using the Pythagorean theorem on the horizontal and vertical pixel counts.
PPI Formula
The formula for calculating PPI is:
PPI = √(width² + height²) / diagonal size
Where width and height are in pixels, and diagonal size is in inches.
Common Display Resolutions
| Resolution | Name | Aspect Ratio |
|---|---|---|
| 1920 × 1080 | Full HD (1080p) | 16:9 |
| 2560 × 1440 | QHD (1440p) | 16:9 |
| 3840 × 2160 | 4K UHD | 16:9 |
| 2560 × 1600 | WQXGA | 16:10 |
| 3440 × 1440 | UWQHD | 21:9 |
| 5120 × 2880 | 5K | 16:9 |
PPI Guidelines by Device Type
- Desktop monitors: 90-110 PPI (standard), 140-220 PPI (high-DPI/Retina)
- Laptops: 100-130 PPI (standard), 200-280 PPI (high-DPI)
- Tablets: 130-170 PPI (standard), 260-330 PPI (high-DPI)
- Smartphones: 300-400 PPI (standard), 400-600 PPI (flagship)
- Print: 300 DPI minimum for quality prints
What is Dot Pitch?
Dot pitch is the distance between the centers of adjacent pixels, measured in millimeters. It's the inverse of pixel density - lower dot pitch means higher pixel density and sharper images.
Dot pitch = 25.4 / PPI (converting inches to millimeters)
Frequently Asked Questions
- What is a good PPI for a monitor?
- For desktop monitors at typical viewing distances (2-3 feet), 90-110 PPI is standard. For sharper text and images, look for 140+ PPI. High-DPI or Retina displays typically have 200+ PPI.
- Why does the same resolution look different on different screen sizes?
- Because PPI depends on both resolution and physical size. A 1080p resolution on a 24-inch monitor has about 92 PPI, but on a 15-inch laptop it has about 147 PPI, making everything appear sharper on the smaller screen.
- What's the difference between PPI and DPI?
- PPI (pixels per inch) refers to screen displays, while DPI (dots per inch) refers to print resolution. They're often used interchangeably, but technically PPI is for screens and DPI is for printers.
- Can the human eye see individual pixels?
- At typical viewing distances, most people cannot distinguish individual pixels above 300 PPI. This is why Apple called their high-density displays 'Retina' - the pixels are too small to see at normal viewing distance.