Take your usual size or size up for extra slouch
Rough size guide XS6-8 S10-12 M12-14 L14-16 XL16-18
Measurements in cm laid flat
Chest - XS52.5 S55 M57.5 L60 XL62.5
Length (Front) XS52 S53 M54 L54 XL56
Length (Rear) XS56 S57 M58 L59 XL60
Rae is size 10-12 and wears size medium in the photos.