I'm 175 pounds and 5'11'' and I got the extra large, and I could just barely get into them.  So know that they run small-- I would say ridiculously small.  Nonetheless I persisted and kept them since it was just for swimming laps and they were comfortable.  About two months later (swimming 3 times a week in a chlorine pool) and these shorts are pretty much trashed.  The waist band is twisted, the ring the tie goes into is gone, and they have totally faded as if left in the sun.  I would not buy another pair of these.