Find Your Fit: Which Soul Seat Size is Right for You?
The difference between the Standard and Large sizes is the size of the lower platform (the butterfly cushion).
The standard size is 25" wide and the large is 31" wide. The legs and perch (smaller cushion where you sit) are the same for both sizes.
Standard: Folks who are shorter than 5’9” 
Large: Folks who are 5’9” or taller
We often recommend going with the large if you're on the fence about which size to choose. The only downside to having the additional legroom of the large would be if your desk or workspace cannot accommodate the additional width, or if you are around 5’2” or shorter.
 
                        