I bought my son a medium. He usually wears a small in men. He is 13 years old. 5'3. So it might run small for others. It fit him PERFECTLY and the material is nice and thick. He hasn't worn it because it just arrived today but after reading reviews, I will air dry it so it won't shrink or fade. The polo sign DOES look balled up tho. Obviously a fake polo shirt. They're kids tho. So they don't pay attention to things like that and they also don't take care of their clothes anyway. Don't recommend for a grown man but it's a good buy for children.