Actually it depends on bone structure for a good size jeans. Also, the average jean size for girls can't be 14, if so it's for women, and more then half of American (and more in England) are over weight. So even if the average size was 14 it doesn't mean it's the best size since the average woman is overwright. For example, on the calculator I am exactly on the 50% mark for 16 year old girls who are 5'4" and I wear anything from a 0 to a 4 (but usually a 2). I am not supper thin either, my stomach is not flat, it is round. Please note, I do not consider myself overweight, I am not trying to lose, I just wanted to say you can't go by pants size alone. Wider hips (not fatter but wider) means larger pants, narrow hips means smaller pants. Jean size doesn't mean anything.