There has been a couple posts on this recently if you do a search. Check your state regulations to see if they have a minimum weight for hunting first. 35-40 is pleny to kill a deer out to 25 yards. That would be my minimum suggestion and most people feel about the same on here with those numbers from the last couple threads but some think it should be a little more. Just find out what her comfortable draw weight is and get a bow that will meet that and be able to be adjusted up from that because she will get stronger at pulling a bow the more she shoots. My guess is you will be buying a 40-50lber unless she is really strong and can pull 48-50lb with ease right now. Good luck. WCL