How Measurements are Taken:

Waist:  For pants and skirts across the very top, then double.  

Inseam:  Measured along the inside leg from the crotch seam to the bottom hem.

Rise:  Measured from the crotch seam up to the top of the waist band in the front. 

Flare:  For pants, measure at the end of the pant leg across the bottom opening (not doubled)