I run 170lbs., 36 d, 5'4" and ordered a regular 14. probably could get away with a 12. i didn't order a petite because i wanted the length. however i ordered the 14 because it is cotton hand wash and thinking there might be some shrinkage. it fits to perfection everywhere - but the waist. it's very loose. they must have clipped it in at the waist in the back of this shot on the model. the picture doesn't clearly show the hi-low concept of the hem. i like that so it isn't a problem. very unique a