You can find this by stretching your arm out in front of you and getting someone else to measure the distance (L) from the back of your neck to your fingertips as shown in the diagram below. Find the ball diameter (Ø) in the table below that corresponds to your arm measurement.

As a rough guide, an average (167 cm tall) UK adult female should need a 65 cm ball and an average (175 cm tall) UK adult male should need a 75 cm ball. If you think you have made a mistake over the size when you receive your ball please contact us.