I'm 5'4 and 160 lbs, normally wear a size 10. I ordered a 12, which zipped but was definitely on the tighter side. The material isn't stretchy at all and this runs a bit small in general. The bigger issue for me was that this is intended for someone with a smaller chest. As a DD, the side without a strap left me very exposed - there just isn't enough material extending past the waist section. Would probably fit well on a single D or smaller.