At the collegiate and professional levels, the men's discus weighs 2 kilograms and has a diameter of 22 centimeters. The women's discus is slightly smaller, weighing 1 kilogram with a diameter of 18 centimeters. In high school, the boys' discus weighs 1.6 kilograms and the girls' weighs 1 kilogram.
In all levels of play, the discus is thrown from a circle 2.5 meters in diameter, according to About.com. Competitors may touch the inside of the rim that surrounds the circle during the throw, but not the outside of it. The thrower must also remain inside the circle until the discus hits the ground or a foul occurs. A U-shaped net surrounds the throwing area to ensure the safety of bystanders.