The diameter of a standard or professional basketball hoop is 18 inches. The backboard of a professional goal measures 72 inches wide by 42 inches tall.
The distance from the top of the of the goal to the floor is exactly 10 feet for standard play. A professional National Basketball Association or Women's NBA court measures 94 feet long and 50 feet wide. The foul line sits 15 feet from the front of the backboard. High school and junior courts differ greatly in size, but the measurements of the backboards and rims are generally the same for all levels of play. For unprofessional leagues or practice fields, all measurements may vary.