Dimensions of the Basketball Backboard. The official backboard in the NBA measures 3.5 feet high and 6 feet wide. Usually, it is made from tempered glass or fiberglass.Somewhere at the middle part of the backboard is a rectangle, which is used primarily for making bank shots. It measures 1.5 feet high and 2 feet wide.he dimensions of the backboard in other basketball organizations such as the Women’s National Basketball Association or WNBA and the National Collegiate Athletic Association or NCAA are patterned after the NBA. The same also goes for high school games and Olympic basketball competitions.