I bought a bunch of these from another vender on here to wear to the gym and they fit great. I normally wear a medium, which in other brands provides me a perfect slim fit for that purpose. It’s not baggy so it doesn’t get in my way and it’s not so tight that I’m constantly pulling at it. This shirt says "M” on the size marker, so I definitely got the right one, but it’s huge. I would compare it more closely to a normal L/XL. I’m 5’8” and a pretty solid 170lbs and this thing hangs off of me like a bed sheet. Either size down or go with a different brand is my suggestion. If you like your shirts long and baggy, it is a really nice quality shirt. The material seems pretty thick.