Most people don’t know how to measure the size of displays like LCD monitors, laptop screens, and LCD TV. It is always advisable to measure the screen size before buying a display device because some manufactures list inappropriate sizes.
Steps to measure a display size
1. Take a measuring tape or ruler (for small screens).
2. Hold the tape diagonally (from the top left corner to the bottom right corner) on the viewable area (the glowing screen only not the borders) of the monitor or LCD screen.
3. Now write down the accurate size in Inches or Cm (Centimetre).
Hope you got it the right way now.