I ordered a size large (as someone who has a small waist but pretty big boobs) and it fit me perfectly. It was stretchy enough in the right areas but gave a nice, close fit around my waist. At first, I thought the shoulders/arms were a little tight but it was okay for me after I shuffled around the fabric a bit.
A word about the fabric is that it is very soft and breathable but quite thin. Definitely not a shirt you can wear dark coloured underwear with if you have the shirt in a lighter colour. I got a pink shirt and a black bra shows right through. That said, I'd be willing to forgive it and try to wear complimenting colours with it as the fit is just so nice.
