erform a simple calculation to match the screen size of a standard TV to that of a widescreen TV. If you currently have a 4:3 TV and you want to continue watching 4:3 on a widescreen TV, multiply the diagonal length of the older TV model by 1.22. The result would be the diagonal screen size that the widescreen TV would have to be to match the old model.
Say you have a 40 inch (102 cm) TV with a 4:3 aspect ratio, but you're thinking about upgrading and you don't want your screen size to get smaller. You'd need to get at least a 50 inch (127 cm) screen to view in 4:3 without your picture getting smaller. That's because 1.22 x 40 = 49. Since 49 inch TVs are generally not made, you'd need to go up to 50 inches (127 cm).