I went by the sizing they recommended for my size. However, they fit pretty good and I don't have too much to complain about, but I am 6ft 3in tall and 280lbs. I work out very regularly and have large muscles. The 2XL fit good, but they were loose (draped) in the lat area under my arms. I ended up ordering the Xl and they fit perfect where it doesn't sag anywhere. I will keep the 2XL, because it isn't bad, but it also gives me room for growth to fill that size in like I do the XL now. So if you