What happens next?

How to measure monitor size
Measure the length of the monitor screen.
Use a ruler to measure the horizontal length of the monitor from one end to the other. Don't include the frame or structure around the monitor, measure only the viewing screen.

Pick from: (A). Measure the height of the monitor screen. Only measure the image area rather than the frame or border around the monitor. (B). Measure the length of the monitor screen from top to bottom. Measure around the screen from top to bottom, starting at the bottom, and moving inward (across the screen). (C). For example, a 12-inch monitor (100 mm) monitor has 12 inches of screen backing and 16 inches of screen side. A 24-inch monitor (150x 2100 mm) monitor can only have 12 inches of screen backing. (D). Bring the measuring tape to the base of the monitor. Cup your index and middle fingers around the monitor to measure from the base of the screen.
(A).