It appears that beavis who is 17 is about 5'2 or 5'3 and butthead who's also 17 is 5'5 to 5'7, but in the beavis and butthead do America movie they are only 3'10
Highland , Tx .
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.
"Frog Baseball" September 22, 1992 (1992-09-22)