I'm 5', 11" tall, weigh 175lbs., and have a dad-bod build. I usually wear a men's size Large shirt. I bought this shirt in a size Large and it is a little more fitted than a typical size Large shirt. If you like a looser fit, I recommend ordering the next size up. The material is thin, light, and goes unnoticed when climbing. It is slightly transparent, so you can see tattoos through it. They say geniuses pick green.