How to select an exercise ball
Sitting on the ball, your hips and knees should form a 900 angle with each other.
Use the information below as an indicator as to the correct size needed:
Ball Diameter User Height
55cm 1.50m (4ft 11in) to 1.60m (5ft 3in)
65cm 1.70m (5ft 6in) to 1.86m (6ft 1in)
75cm 1.88m (6ft 2in) to 2.07m (6ft 8in)
85cm 2.10m (6ft 9in) and taller.