Well if I could choose too small and too big I would. So I'm 5'4.170 so I have medium. The shirt is a little tight, but that's not a big deal as I want to wear it under my clothes anyway. However, the bottom is long and bulging. Baggy pants make it impossible for you to stay warm. But they keep you warm! I rode my motorbike home completely under jeans and a riding jacket in 23 degree Californian weather and wasn't freezing! Needless to say they keep you warm but the sizing isn't right. I contacted customer service to see if I could exchange a medium bottom for a small bottom and they said NO, unfortunately I would have to return the entire set. Maybe they'll change their minds and I'll update this review to 5 stars as if to leave.