I am a 34D chest and I ordered a small. Small worked everywhere but the area under the underarms. Too big... I has to be taken in. If you have a meatier rib cage then it might work.

I'm usually a medium. I purchased a large based on the size chart, but should have gotten my original size medium or maybe even a small. The shirt is very flowy and baggy, didn't expect that. I tucked it in and it looks great.