Im 5'1" 38 bust 100lbs and I went by the size chart and got a medium.
Since most are from China I thought that size might be right even though I would normally buy a small BUT this robe goes to my ankles and will drag on the floor if I bend over and it wraps around me a bit too much. I kept it because it is warm, thinker than others I have and very cozy. Even though I could have got the small and been safe if the sizes are consistent I am still happy with my bit over sized robe.