I am 5' 8 1/2'' with a chest of 38'' athletic build. I chose a small and it fits great. If you like a fitted shirt, choosing a small will be best for your build. My weight really doesnt matter since my height and chest size are given since those are the defining measurements that actually plays a role in fitting but my weight is 160lbs. I took off one star because of the sleeves being too flimsy. Sure you can say get bigger arms but this being a fitted shirt should also have a fitted sleeves with the opening a little be tigher. People who work out like feeling their biceps rubbing against the sleeves of their shirt. It makes them feel more power just like wearing compression shirts or pants.
Rating: [4 of 5 Stars!]