The kettlebell or girya (Russian: гиря) is a cast iron weight looking somewhat like a cannonball with a handle. Many companies produce their own brands of kettlebells and kettlebell exercise programs. Some modern kettlebells feature adjustable weights or are rubber coated to improve safety for floors.

While today, there are sizes that range from 5 lbs to 175 lbs, the traditional Russian kettlebell is usually one which weighs 1 Pood (roughly 16kg / 35lbs).

Unlike traditional dumbbells, the kettlebell's center of mass is extended beyond the hand, similar to a Clubbell. This allows for swing movements not possible with traditional dumbbells. Because more muscle groups are utilized in the swinging and movement of a kettlebell than during the lifting of dumbbells (particularly posterior chain and core muscles), a kettlebell workout is sometimes claimed to be more effective, and yields better results in less time (dependent on training goals).

Because the center of mass on a kettlebell "swings", micro-muscles are needed to balance a kettlebell, more so than a dumbbell. The existence of a handle allows for "release moves" which are not available to a dumbbell.

Variants of the kettle bell include bags filled with sand or steel shot. They also have a center of mass extended beyond the hand and allow for swing movements and release moves with added safety and added grip, wrist, arm and core strengthening due to the shifting fill material.