Turn off the monitor if needed and clean the screen edges for easier measuring
Measure only the visible screen area, not the outer bezel or frame
Use a tape measure or ruler
Measure diagonally from the top-left corner of the visible display to the bottom-right corner
Record the measurement in inches
If needed, measure the width and height separately from edge to edge of the visible screen
Check the aspect ratio if you want to verify the screen size
For laptops, measure the display panel only, not the body of the laptop
For curved screens, follow the diagonal across the visible display as closely as possible
Compare the measured diagonal with the manufacturer’s listed screen size