After studying some reviews, I ordered a small (normally wear a medium). I am 5'2, 124 lbs. Waist measures 30', bust and hips both measure 37'. If you're waist is any bigger, definitely go to a medium as mine has absolutely no extra room. Other reviews stated that it is no good for big chests, but I feel that it gives really good support!  The one down is this is definitely not a romper that I would ever be able to put on by myself, so keep that in mind before you order it! I was able to successfully hook one strap but after struggling with the other one for 5 minutes, I realized my husband would need to help. I was able to remove the romper by myself though! Great buy.