the best advise I can give is to buy the larger size. I'm 5'9", 200lbs, athletic build and I definitely needed an x-large. The pants are elastic and you can pull them up to your armpits if needed. I tucked mine in my socks to give the impression I was wearing boots. The material is flimsy & light but doesn't fall apart. The inner shirt is literally a bib that ties around the back. It all worked for my purposes but if you want to wear a real shirt & tie, the jack would accommodate it. Enjoyed every second I had it on!!!