I would normally wear a size small. This small is more an XS. It does stretch, but then it is super see-thru to begin with, so it is just more pronounced. Only reason I didn't rate it lower is that I got the white tanks as an add on for $3 each, so Im not out a fortune. For reference, I am currently 125lbs at 55. P.S. the white is not a bright, crisp white either. 