For slim fitting dress shirts, forum wisdom says to go up 3 inches from your actual chest size. (See: here) So if you have a 41 inch chest, you go for a shirt that is about 22 p2p (or 44 inches all the way around). But what about for polo shirts? The pique material usually stretches quite a bit. Does 1.5 inches up from actual chest size sound right? On a 41 inch chest, this would mean about 21.25 p2p.