What age can they shave, I would say whenever the hair shows. But what age should they start shaving, 14 and up. The fact is that once hair is shaved it doesn't come back thicker and stronger but needs a relatively constant upkeep, which may be heavy for younger girls . Anyway, if the hair on a body part is barely visible it might not be shaved at all. Once you initiate the process of shaving, it has to be repeated regularly otherwise it grows back prickly, only at first, but it may be a hassle to wait until it fully grows back. However, if the hair is dark, noticeable and thick, shaving is needed, if it bothers the girl.