Is 140 pounds a good weight for a 15 year old girl who is 5 foot 4-ish?

You should try lose a little weight, but don't worry about it much, 14 yr old are growing and therefore shouldn't be stick thin. If she does sport it might be muscle, rembember muscle weighs more than fat. Also if she is uncomftable with how she looks i would advise losing weight, but if not stick as is. Bella. x