I'm 5'7 140 lbs and I ordered a medium since the reviews said it ran small and it fits perfectly! I love this swimsuit but the only bad thing about it is that you can totally see the pads in the top through the suit and it looked really bad. Once I took the pads out though it was fine!
You can see the padding through the top & my bottoms were VERY cheeky. I'd be careful with ordering especially if you have a bigger butt than a chest because it won't cover it all. Other than that, I love this bathing suit!