How Old Is Bobby Hill?

Through the course of the series, Bobby gets older. He begins the series as an 11-year-old, becomes a 12-year-old in "Shins of the Father" (the episode was released in 1997, placing his birthdate in 1985), a 13-year-old in "I Don't Want To Wait For Our Lives To Be Over," and stays that age for the remainder of the show.