PPI Calculator
Calculate pixels per inch (PPI) for any screen from its resolution and diagonal size. Compare displays, check retina threshold, calculate print DPI size, and analyze pixel pitch.
Extended More scenarios, charts & detailed breakdown ▾
Professional Full parameters & maximum detail ▾
Display Density
Pixel Count
Viewing Analysis
How to Use This Calculator
Enter your screen's horizontal resolution, vertical resolution, and diagonal size in inches to get the PPI instantly. Use the Print DPI tab to find print dimensions for an image. The Compare Displays tab puts two screens side by side. The Professional tab adds pixel pitch, dot pitch, subpixel count, retina threshold analysis, and device presets for iPhone, iPad, MacBook, and 4K TV.
Formula
PPI = √(H² + V²) ÷ diagonal (inches)
Pixel Pitch (mm) = 25.4 ÷ PPI
Retina threshold ≈ 57.3 ÷ viewing distance (ft)
Example
27-inch 2560×1440 (QHD): diagonal px = √(2560²+1440²) = 2937.4 | PPI = 2937.4 ÷ 27 = 108.8 PPI
Frequently Asked Questions
- PPI (pixels per inch) measures the pixel density of a screen. Higher PPI means sharper images. It is calculated by dividing the diagonal pixel count by the physical diagonal size in inches.
- Apple defines a retina display as one where individual pixels cannot be distinguished at a typical viewing distance. For phones (~12 inches), this is roughly 300+ PPI. For desktop monitors (~24 inches), ~110 PPI is sufficient.
- Pixel pitch is the physical distance between pixel centers, usually measured in millimeters. It is the inverse of PPI: pixel pitch (mm) = 25.4 ÷ PPI. Smaller pitch = higher density.
- A 1920×1080 display on a 24-inch panel: diagonal pixels = √(1920²+1080²) = 2202.9. PPI = 2202.9 ÷ 24 ≈ 91.8 PPI.
- PPI (pixels per inch) refers to screen pixel density. DPI (dots per inch) refers to print resolution. For screen-to-print, use the Print DPI tab to find the physical print size for a given image resolution and DPI.