The minimum weight of a rhythmic gymnastics ball is 400 grams. FIG specifications also set its diameter at 18 to 20 centimetres, creating an apparatus that is light enough to be tossed yet substantial enough to remain stable during catches and rolls.
Rhythmic balls are made from rubber or a synthetic material with similar properties. Unlike a ball used in ordinary games, the rhythmic apparatus must be handled mainly through balance, rolling, bouncing, throwing and catching rather than being gripped tightly. During a routine, gymnasts may support it on the hand, arm, shoulder or other body surfaces.
The weight is often confused with the ball’s diameter, or with the specifications of other rhythmic apparatus such as clubs and hoops. A ball can be brightly coloured or decorated, but appearance does not replace the technical requirements. The minimum-weight rule helps keep the apparatus consistent across international competition while preserving the sport’s emphasis on continuity and expressive movement.