| Your height | Ball size |
|---|---|
| 4ft 11 to 5ft 8 (150 to 173cm) | 65cm |
| 5ft 8 to 5ft 10 (173 to 178cm) | 65cm or 75cm, see below |
| 5ft 10 and over (178cm+) | 75cm |
Quick answer: 65cm if you are up to about 5ft 8, 75cm if you are taller. In the overlap, pick the 65cm if you want to sit lower and bounce more, the 75cm if you have long legs or plan to use it as a desk seat afterwards. Once it is inflated, your hips should sit a touch higher than your knees with your feet flat. That is the test.
Which size birthing ball do I need?
Put your height in feet and inches, or in centimetres.
If you're under 4ft 11, the 65cm still works, slightly under-inflated so you sit a little lower. There is no 55cm in the range because at that size most adults end up with their knees higher than their hips, which is the opposite of what you want in pregnancy.
The 65cm outsells the 75cm nearly two to one, so if you are stuck between them, the 65cm is the safer pick.
The sit test once it arrives
Inflate it, let it sit overnight, top it up, then sit on it with your feet flat and hip-width apart. Knees at roughly a right angle, hips just above them. If your knees are above your hips, add air or go up a size. If you feel perched and your feet want to lift, let a little air out.
Inflating properly takes longer than people expect and is the thing we get asked about most: room temperature first, then two goes with a day between them. The electric pump does the work in minutes if you'd rather not hand pump.
The ball, in your size
BABYGO® Birthing Ball, 65cm
With the hand pump, or with the electric pump. Anti-burst, tested to 1000kg, and it comes with the 100 page BABYGO® pregnancy book. Eight colours.
BABYGO® Birthing Ball, 75cm
Same ball, same book, same pump options, a size up for anyone over about 5ft 10.
On a wooden or tiled floor the stability ring sits under the ball and stops it drifting when you sit down and stand up, which matters more the bigger you get.
Questions we get asked
What size birthing ball for 5ft 4?
65cm.
What size birthing ball for 5ft 8?
Either. The 65cm if you like to sit lower and bounce, the 75cm if your legs are long in proportion or you'll use it at a desk. If in doubt, the 65cm: it is the one nearly two thirds of customers choose.
Is a 55cm ball too small for pregnancy?
For most adults, yes. Below about 60cm your knees end up above your hips, which tips the pelvis backwards, the opposite of the open, forward tilt you sit on a ball for. That's why we don't sell one.
Is a birthing ball the same as a gym ball?
Same shape, different build. Ours has a 2000 micrometre wall, is anti-burst rated so a puncture deflates slowly rather than popping, and is tested to 1000kg. A cheap gym ball is none of those things, and you'll be sitting on this one at 39 weeks.
How do I know it's inflated enough?
The sit test above. If your hips are below your knees it needs more air; if it feels hard and you slide, a little less. New balls stretch: pump, leave overnight, top up.
General guidance from the BABYGO® team, updated 16 September 2026. If you have pelvic girdle pain or have been told to limit activity, check with your midwife or physio before starting ball exercises.
