S  M L
PTP 18.5"  19.5" 20.5"
Waist (unstretched) 12" 13" 14"
Waist (stretched) 17"+ 18"+ 19"+
Length 16" 16.5" 17"

*Model is 1.68m, UK 6 (PTP15.5", Waist 12.5") and wears size S.

If you are in between size for PTP/Waist, it is best recommended to size down.

*In between sizes refers to your measurements falling between 2 sizes, example size S & M.