Ordering clothes through Amazon is a bit tricky, definitely scroll through as many reviews as possible. Im 52, 128lbs with a softer athletic build and typically wear a Medium in everything. I ordered a Large in Red, Luckily it fit as I had hoped, though next time I may order an XL for slightly a looser fit around my belly. :) Definitely AIR DRY or it will shrink. I also feel that the material may change with different colors (dye).- I am picky with material but Im greatly satisfied with this shirt, for ME, it was not see through and thick/comfortable enough.