^ I own a ILU short sleeve shirt in size S.
I'm 5' 9 and a pretty slim guy, the fit of the shirt is pretty slim and long indeed, but I like it when shirts are a bit longer in length. The slim fit isn't a problem for me, but If you're very muscular, the fit might be too slim.
I would suggest to measure one of your own shirts, and check the size chart at the ILU webstore to see what size fits best.
Cheers dude, so many size charts I use though seem the only work in theory. I'm no popeye so I hopefully it will fit ok. I guess I'll be cheeky and get an ILU shirt in medium off Urban Industry, try it on for fit, keep it tidy and then return it (they only have the long sleeve version at the moment, i want short sleeve)