Measure around your waistline, keeping the tape comfortably loose .

Measure pants that fit you well. Lay them flat and measure from the crotch to the 
bottom of the let hem. If you don't have suitable pants, measure from your crotch to 
your desired pant leg length.

H to H = Wait Around
C to D = Half Center Around
H to F = Full Length
D to G = Half Length