Pixel Density Calculator - PPI Calculator
Calculate a screen's pixels per inch (PPI) from its resolution and diagonal size.
Pixel Density
91.8 PPI
Diagonal: 2202.9 pxHow to Calculate Pixels Per Inch (PPI)
Pixel density (PPI) measures how tightly packed the pixels are on a screen. Enter the screen's resolution (width and height in pixels) and its diagonal size in inches to find the diagonal pixel count and divide it by the diagonal size.
Example
A 1920×1080 monitor with a 24-inch diagonal has a diagonal pixel count of √(1920² + 1080²) ≈ 2,203.1 pixels, giving a pixel density of about 2,203.1 ÷ 24 ≈ 91.8 PPI.
Common Use Cases
- Comparing sharpness between two monitors, TVs, or phone screens.
- Deciding whether a display's resolution is high enough for its physical size.
- Checking a screen's pixel density before a purchase.
FAQs
What's the difference between PPI and DPI?
PPI (pixels per inch) describes a digital display's pixel density, while DPI (dots per inch) traditionally describes a printer's or scanner's output resolution in physical ink dots — the terms are often used interchangeably in casual conversation, but PPI is the technically correct term for screens.
What PPI counts as sharp or "retina"?
It depends heavily on viewing distance: phones held close to the face typically need 300+ PPI to look sharp, while monitors and TVs viewed from farther away can look just as crisp at 90-110 PPI. There's no single universal threshold — it's a function of both PPI and how far away you view the screen.
Can I enter the diagonal size in centimeters instead?
Convert centimeters to inches first (divide by 2.54) before entering the diagonal size, since PPI is inherently a per-inch measurement and the formula expects the diagonal size in inches.