What Is My Monitor PPI?
Calculate your monitor PPI from screen size and resolution
Your Monitor PPI
Enter your screen size to calculate
Screen Resolution (CSS)
0 x 0
Device Pixel Ratio
1x
Physical Resolution
0 x 0
Formula
PPI = sqrt(02 + 02) / diagonal
How it works
PPI (Pixels Per Inch) is calculated by finding the diagonal pixel count using the Pythagorean theorem on your screen's physical resolution, then dividing by the screen's diagonal size in inches. Your physical resolution is determined by multiplying screen.width and screen.height by the devicePixelRatio. Displays with a DPR greater than 1 are considered Retina or HiDPI displays, meaning they pack more physical pixels into each CSS pixel for sharper rendering.
Frequently Asked Questions
What is PPI and why does it matter?
PPI (Pixels Per Inch) measures the pixel density of your display. Higher PPI means smaller, denser pixels, which produces sharper text and images. A typical desktop monitor is 90-110 PPI, while Retina displays are 200+ PPI.
How is monitor PPI calculated?
PPI is calculated by dividing the diagonal pixel count by the screen diagonal in inches. The diagonal pixel count comes from the Pythagorean theorem: √(width² + height²). For a 1920×1080 display at 24 inches, that's √(1920² + 1080²) / 24 ≈ 92 PPI.
What is a Retina display?
Retina is Apple's marketing term for displays with a pixel density high enough that individual pixels aren't distinguishable at a normal viewing distance. Generally, this means 200+ PPI for handheld devices and 100+ PPI for desktop displays viewed from further away.
Does higher PPI mean better display quality?
Higher PPI means sharper detail, but display quality also depends on color accuracy, contrast ratio, brightness, and panel type. A high-PPI display with poor colors won't look as good as a moderate-PPI display with excellent color reproduction.
Why do I need to enter my screen size manually?
Browsers can detect your screen's pixel resolution but not its physical size in inches. There's no web API to read the actual dimensions of your monitor, so you need to input the diagonal measurement to calculate PPI accurately.