Screen Size Calculator - Width, Height, Aspect Ratio & PPI from Diagonal
Screen Size Calculator
Turn a screen's diagonal into its real width and height
Real Dimensions
A 27-inch 16:9 monitor is about 23.5 by 13.2 inches. See it for any size and ratio.
Pixel Density
Add the resolution to get PPI, dot pitch and the distance at which pixels blend together.
Either Direction
Start from the diagonal, or measure width and height and find the diagonal.
Full Privacy
Everything is calculated in your browser.
From Diagonal to Width and Height
Screens are sold by their diagonal, but what you fit on a desk is the width and height. For an aspect ratio of w:h, the width is the diagonal × w ÷ √(w² + h²) and the height is the diagonal × h ÷ √(w² + h²). A 27-inch 16:9 screen is therefore 27 × 16 ÷ 18.36 = 23.5 inches wide and 13.2 inches tall, and at 2560 × 1440 pixels its density is about 109 pixels per inch.
Pixel density is the diagonal in pixels divided by the diagonal in inches. The "pixels blend from" figure is the distance at which one pixel covers one arcminute, the finest detail a typical eye resolves, so from further away than that you cannot tell the pixels apart. Marketing sizes are nominal and real panels can differ slightly, so measure if a fit is tight.
Key Takeaways
- Common ratios built in: 16:9, 16:10, 21:9, 32:9, 4:3 and more, or your own.
- Resolution presets: From 720p to 8K, or type your own.
- Nominal sizes: Real panels can differ a little from the label.