So Kakashi is 12 years old in kakashi gaiden.
Four generations of Huo Ying died at the age of 24, when Naruto was just born and pregnant in October, so she married nine planets Nye at the latest at the age of 23. Namikaze Minato in kakashi gaiden is not a hokage, because the four generations said to Kakashi, "From today on, Kakashi is as tolerant as my level." So the fourth generation was about 2 1 to 22 years old.