I typically wear a M in pants or undies, sometimes an L. I got both an L and M in this style. The L was still too small that is, it fit, but it was pretty high up on the bottom, and the bottom rides up all day. The M was smaller still, but didn't ride up as much (because it didn't have any further up to go!). I also found the most important area to be too narrow, which was really annoying.

The waistband is good and the fabric is nice, but they are annoying to wear.