I'm very happy with this rash guard. I'm 5'6 136lbs 34/28/38 and I ordered the small. It fit well, not too tight or too loose. I wore this all day for 2 days at a water park in mid 90 degree sunny weather and did not get burned so it works. It is very hot until you get wet and then I was comfortable so I wouldn't recommend it for hiking or general shirt. But as a rash guard in the water it is perfect.