XS S M L XL
PTP
15.25" 16" 17" 18" 19"
Waist 12.25" 13" 14" 15" 16"
Hip 17.25" 18" 19" 20" 21"
Length 32" 32.5" 33" 33.5" 34"

*Model is 1.73m, UK 4/6 (PTP15.5", Waist 12", Hips 17.25") wears size S.

If you are in between sizes for PTP, it is best recommended to size down.
If you are in between sizes for waist, it is best recommended to size up. 

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