If the screen is 20-27 inches, you should be 2 meters away from the TV 1.
If the screen is 32-37 inches, you should sit 2-3 meters away from the screen.
If the screen is 42-46 inches, you should be separated from the TV screen by 3 to 4.5 meters.
If the screen is 50 inches, the best viewing position should be 3.5 to 5 meters away from the screen.