The viewable rectangular screen dimensions for an exactly 20 inch diagonal television would be 17.44 inches wide by 9.80 inches high. In reality, 20 inch TV screen dimensions will likely vary slightly by a fraction of an inch either more or less, as television screen size classes are rounded to the nearest whole inch. Keep in mind, the bezel adds a bit more width and height to the television’s actual overall dimensions, and its pedestal stand adds some height if you don’t wall mount the TV.