These are really soft and super stretchy and very comfortable! I am 5'3 and 125lbs and I ordered the small. Since I carry my weight in my lower half, they are not really loose fitting. From the knees up they fit more like leggings and then the knees down to the feet are loose. If you like your pjs looser then consider ordering up a size (as I wish I had). They are a little long for me (I have short legs) but I wear slippers around the house so they rest on top of my shoes and don't drag on the ground. I haven't washed them yet so I expect them to shrink somewhat afterwards.