Usually wear a small, sometimes medium. bought this in medium and am very happy with it. form-fitting but not too tight. would probably fit well in a small, if i was in better shape. it does show any flaws, so the medium is more forgiving. bought the black and am considering the neutral stripe. this is a great, medium weight top for cooler days. the snap collar looks nice open. i plan on washing on delicate and hanging up to dry. i never dry clean anything except wool suits and coats.