I purchased a size medium in this workout top. I absolutely love the comfort of the material and the mesh on the back. I had to go up a size cause it did fit exactly with the size small, but it was skin tight when I tried to close the ends of the shirt on the back. The medium is perfect for a little bit looser fit and with enough room to tie the shirt. If you plan on keeping the shirt open in the back (which is still cute, since it shows some skin), then get your exact size you currently wear. I have one in a small and one in a medium. It is also very breathable and feels great when working out outdoors. I just purchased a couple more colors today.