So I bought the XL (which I think corresponded to size 16-18 according to their sizing chart) Im 56 / 170 with a bra size of 38C.  Im more like a 10-12. I chose to purchase the XL based on reading a number of reviews, so the suit fit as expected based on th reviews not on the sizing chart provided by the company. (I would have given this 5 stars but for the sizing issue.) If you have stats similar to mine, I recommend going with the XL. This fit perfectly in the size I chose and is very comfortable. It does show some cleavage but my boobs didn't seem like they were bursting out. I also didn't feel like the suit was too short like some other suits were (but this could be because I sized up).  I ordered this in navy and its a really pretty shade and the material is nice. Im very happy with this-I haven't tried it in the water yet though.