Generally speaking, the size of your TV should be about ⅔ of the width of your cabinet. Because TVs are marketed based on the screen's diagonal measurement, knowing the screen's actual width can be a little tricky. If you have an empty space in your cabinet or built-ins, measure the space, then allow at least two inches of space on each side of the TV. From that measurement, you can determine what size of TV you can purchase for the space.