I usually wear a medium but in this top probably could have pulled off a small however i was afraid the neck would be too tight.  was considering the small because the arm holes were a bit baggier than i would like.  no issue with my bra showing though.  i wasn't able to try on the small to test my theory since i purchased online.  overall i love the color (blue), the fabric is comfortable, definitely loose but i'm okay with that on a hot sunny day.