The advertised size of a TV say 55 inches refers to the diagonal measurement of the visible screen only, from one corner to the opposite corner.
32-Inch TV Good for a Dorm Room and go-to choice for most dorm setups. From a 5-foot distance, a 32-inch screen feels natural not too big, not too small.
In most 12×12 rooms, the best TV size is between 50 and 65 inches. This range balances screen size with viewing distance without overpowering your space.