Under Armour - What size to get

[mizuno]

What size should I get ?
I normally wear a meduim shirt but really should wear small exceot for my gyne 

[Aperture]

A lot of people suggest you get one size smaller than your t-shirt size, so in your case, you should buy a small.

Even though i'm a small (t-shirt) my current compression vest is a medium, so i'm really not sure which one to get.