My boyfriend is a 18.5 dress shirt size. 6 ft 260lbs bought a 3x and it fit perfect. He had a lot of compliments. Ordered last min for a masquerade quinceaera was worried it wasn't going to come in time because I had ordered the same type of vest from another seller and the order was never processed. So thankful they were fast and the quality was as expected. Will buy from them again.