Exercise ball size guide

The size chart by height

All three of our balls come in the same four sizes. This is the chart printed with them, with the height each size is meant for and the desk height it pairs with if you sit on it at work.

If you are 5'7" or 5'8", right on the line between two sizes, let your legs decide: longer legs for your height point to the bigger ball, a lower desk to the smaller one.

Check the fit sitting down

Inflate the ball, sit in the middle of it and put your feet flat on the floor, about hip width apart. Your hips should sit level with your knees or a little higher, with your thighs close to parallel to the floor. If your hips sink below your knees, the ball is too small or not full enough. If your heels lift, it is too big or too firm.

Inflating and firmness

Our ridged ball and our anti-slip stability ball come with a foot pump, two air plugs and a plug remover. Pump the ball until it reaches the size on the chart, push the plug in firmly, and keep the second plug as a spare. The product notes leave firmness to you: a softer ball sinks more and feels steadier to sit on, a firmer one rolls more easily under you.

Sitting on a ball at your desk

The desk heights in the chart are there because many people use a ball as a seat. Treat it as a seat you can move on, and stand up and walk away from it during the day. If you have a back problem, ask your doctor or physical therapist before you swap your chair for a ball: we do not claim a ball fixes posture or back pain.

If you are pregnant

If you are pregnant, here is what the American College of Obstetricians and Gynecologists says in its patient FAQ on exercise during pregnancy. If you are healthy and your pregnancy is normal, it is safe to continue or start regular physical activity, and you should talk about exercise with your ob-gyn at your early prenatal visits.

ACOG also notes that pregnancy relaxes the ligaments around your joints and shifts your center of gravity, which makes you less stable and more likely to fall, so it advises against jerky, bouncy or high-impact moves. It suggests avoiding lying flat on your back for long, and it lists warning signs that mean you should stop and call your ob-gyn, among them bleeding, dizziness, chest pain and regular painful contractions. Whether and how to use a ball in pregnancy or in labor is a question for your ob-gyn or midwife, not for us.

Every ball in the Gruper lineup comes in 45, 55, 65 and 75 cm, so the chart above works for all three. Compare them on the yoga and exercise balls shelf.