im pretty sure they are 16 years old
yes they speaked it on the 4 episode on the first season just look it up.
Beavis and Butthead are NOT brothers. There Best Friends That Live Togeter.
It is believed that Beavis and Butt-head are 17 or 16 because in Safe Driving which aired in 1994 that they are born in 1978, well, beavis is anyway.
it was rated tv 14 but the game was teen and the gameboy version is rated E 10