This shirt is super comfortable and very stretchy (which I love because it acts like a fitted shirt).
I'm 5'9" and weigh 180lbs and am technically a size medium, HOWEVER, I got a size SMALL because I read in the comments that the shirt is so stretchy and will easily fit around the shape of your body. Which was definitely true.So glad I took a chance and went down one size because I wouldn't have been able to take advantage of the "fitted" nature of the shirt otherwise.