I am 54 and 130lbs and medium is a comfortable fit on me...still loose. It is super cute and soft. The only reason I took off 1 star is because the band that separates the upper chest part from the flowy bottom part is kind of scratchy and itchy.
Also, I want to add that depending on your modesty level, I don't think this is appropriate to answer the door in, walk out to get the mail in or walk around in while in the presence of a teenage son. It's a bit see-through in the chest area.