I wear a size 6 jeans. I bought the size small based on their chart. The bottoms were very small, and the top fit, but just barely. Not an issue of fitting around me torso, but the front of the top was very short. Too short for me to feel secure.
But with free returns, I sent it back in exchange for the medium. This one fits much better. I think the bottoms are a bit too snug for my taste, but the top and tank fit perfectly, so I am keeping it and might wear it with the bottoms from another suit.