Swipe the chart sideways to see every size.
| Size | S2 | S3 | M3 | M4 | L4 |
|---|---|---|---|---|---|
| Back length (cm)seated, hips at 90°, from the base of the neck to the seat | 50 – 58 | 50 – 58 | 59 – 67 | 59 – 67 | 68 – 76 |
| Pelvis circumference (cm)around the hips, over the widest part | 80 – 90 | 90 – 100 | 90 – 100 | 100 – 110 | 100 – 110 |
The size code pairs the two measurements: the letter is the back length (S 50–58, M 59–67, L 68–76) and the digit is the pelvic support size, so S2 is back S with pelvis 2.