Monitor size calculator
Estimate width and height from a screen diagonal and aspect ratio.
Estimate screen dimensions
Use a diagonal and aspect ratio to calculate the geometric width and height. This is a calculation, not a measurement of your monitor.
This estimates the active rectangle from the measurements you enter and excludes the bezel. To reduce pixel width and height into a ratio, see the aspect ratio calculator.
How screen size is calculated
A display diagonal and aspect ratio define a right triangle. The calculator divides the diagonal in proportion to the width and height values you enter. For a 27-inch 16:9 display, the active area is about 23.5 inches wide and 13.2 inches high.
For an aspect ratio written as a:b and a diagonal d, width is d × a ÷ √(a² + b²); height uses d × b ÷ √(a² + b²). The values are converted to centimeters when you select cm.
What the estimate includes
The result describes the rectangular active area only. It excludes the bezel, stand, speakers, and rounded corners. Manufacturers may round advertised diagonal sizes, so use the result as an estimate rather than a tape-measure reading.
If you know pixel width and height instead of a physical diagonal, calculate the ratio with the aspect ratio calculator. The browser resolution report shows values exposed by this browser and cannot measure the physical dimensions.