These pants are made of soft GOTS certified organic cotton, it has a good amount of stretch from the 5% Spandex content.  They have a wide flat waistband.  You will want the waist/hips measurement to be smaller than your body measurements so that they stretch over you and stay up. 

Lucy Wears a M  - Tine wears an S.

S M L XL
Waist 68cm 74cm 82cm 90cm
Hips 88cm 96cm 102cm 110cm