Radius of a Basketball Rim
The diameter of a regulation-sized basketball rim, used in the NBA, NCAA, and high school, is 18 inches.
The International Basketball Federation official rules specify that the rim has a minimum inside diameter of 450 millimeters and a maximum of 459 millimeters. This approximates to 17.7 to 18 inches, in which case the rim radius is about the same as the NBA standard 9-inch radius. The rules for ball circumference allow for a minimum of 29.4 inches and maximum of 30.7 inches.
Based in London, Eleanor McKenzie has been writing lifestyle-related books and articles since 1998. Her articles have appeared in the "Palm Beach Times" and she is the author of numerous books published by Hamlyn U.K., including "Healing Reiki" and "Pilates System." She holds a Master of Arts in informational studies from London University.