I'm 5'8" 172lbs and ordered a large. It fits perfectly snug. Good quality for a good price. If you are looking for a looser fit, I recommend sizing up.

I ordered an XXL. I’m 5’10” and 200lbs. It WAY too tight and fits oddly. Might just be my body shape. Cheaper Amazon ones fit better. I do like the thinness of the material tho. I’ll have to send mine back.