I love these and have ordered 4 more pair of them recently.  The idea of this type of clothing is that it compresses against your skin so you need to buy a size that is 'tight' on you.

I have a 36 inch waste and a 32 inch inseam...and I ordered a large.  Just as the picture for the item suggests the length goes to the area above my ankles. and the top fits snug.  They fit fine, but they don't ride high on the waste all. I would consider it a low rise item.

Keeps me warm, mission accomplished.