Turn off the monitor if needed and clean the screen surface
Use a measuring tape or ruler
Measure only the visible screen area, not the bezel or frame
Measure diagonally from one corner of the display area to the opposite corner
Record the measurement in inches or centimeters
Measure the width from left edge of the visible screen to right edge
Measure the height from top edge of the visible screen to bottom edge
Check the aspect ratio if needed
For laptops, measure the screen only, not the outer casing
For curved screens, follow the curve only if the manufacturer specifies it; otherwise measure straight across the visible area
Compare your measurement with the monitor’s listed screen size if needed