If you follow their size chart you should have no problem with sizing. I tried to order my usual sizing that I wear in other clothing brands and ended up getting a sports bra that was too big on me. When I followed their size chart, it ended up fitting percetly. On the size chart for this sports bra they describe this as a "Sexy Tight Stretchy Fit" and it certainly fits just as they describe. I have a 30.5" waist and wear a 34 B for regular bra's and I went with the medium size. If you don't want it tight and fitted, bump up one size. Would definitely recommend!