Court Lengths and Widths
The largest difference between the basketball courts of the world's governing bodies is in court length. The NBA and NCAA share a 94 foot court length and 50 foot width, while FIBA's court is slightly smaller at 91.86 feet long (28 meters) and 49.21 feet wide (15 meters).
High school basketball courts are typically shorter, at 84 feet long and 50 feet wide.
Basket Height and Diameter
Basket height and diameter is the only measurement that is completely uniform across all governing bodies, with the rim being 10 feet off the surface of the floor and 18 inches in diameter.
Three Point Line Distances
Basketball courts across all levels have similar court markings, denoting the three point line, free throw line, center circle and key.
The three point line arch on an NBA court is, at its peak, 23.75 feet from the center of the basket, but the distance decreases to 22 feet if a player is shooting from the sides of the court.
On an NCAA court, the three point line is a uniform 20.75 feet, while a FIBA court's three point distance is 20.5 feet, and high school courts have a three point distance of 19.75 feet.
Free Throw Line Distances
Free throw line distance is a uniform 15 feet from the center of the basket for all governing bodies, besides FIBA, where the line is at a distance of 15.09 feet (4.6 meters). The free throw line also serves as a boundary for the key.
Center Circle Diameters
The center circle, the area in the center of the court where players contest jump balls, is a uniform 12 feet in diameter for all governing bodies, besides FIBA, where the circle is 11.81 feet in diameter (3.6 meters).
Lengths and Widths of the Key
The key is a typically shaded, somewhat restricted area of the court, primarily used to keep players from positioning themselves very close to the basket for prolonged periods. The key is bounded on the ends by the end line under the basket, marking the out of bounds area, and the free throw line.
In the NBA, the key is 16 feet wide by 15 feet long. At the NCAA and high school levels, the key is 12 feet wide by 15 feet long.
The key on a FIBA court is a trapezoid, rather than a rectangle, measuring 11.81 feet (3.6 m) at the free throw line and 19.69 feet at the end line (5 m).