he is 29...when he was with obito and rin, they were 13 and kakashi is at least 16 yrs older than naruto because in the gaiden, minato wasnt hokage yet and he "died" when he sealed the fox in naruto so i suppose he naruto was born the same year as the end of the kakashi gaiden...so add approx 16yrs to 13 and you get 29