I'm hot natured, and this is a very cool feeling shirt. IT looks cool also.Great shirt at a bargain price. I'm 5'11', 210 very muscular build in my upper body but thin in my lower body.I ordered an XL, it's slightly too tight around the arms and the chest, but it shows off my body well so I'm going to keep it and wear it. For someone with an average build, their normal size should be fine. For someone built like a bodybuilder with a large chest and arms, then order a size up. A 2x may have fit me a bit better.