Dylan says on 17/Nov/09
Definately below 5'6", you only have to look at him in the early episodes of Baywatch walking barefoot in the sand in his swimming trunks with the girls in bathing costumes. Several of the actresses were recorded as below 5'6" yet seemed considerably taller than him and as they were all barefoot I think we can safely assume he was around 5'4"

sarah says on 3/Aug/09
yea he is pretty cute. Though probably he is just around 5'4'', I mean he was already in his 20's during Happy Days, I doubt he grew up 2 inches after that.

Cæsar says on 7/May/07
He's always had the exact same build and oddly enough, a similar face to 5'4 and 1/2 Emilio Estevez. He is not tall, but as someone said below, he is a very attractive man, especially for his age of 44, and I would gladly shrink down to 5'5-5'6 if I could look like him.

X says on 4/Apr/07
Yessssssssss, He was Roger's little brother "Flip" on Happy Days and wore all those half-shirts.

He did appear to be shorter than the Fonzie character.

sf says on 20/Mar/07
On Happy Days, he was clearly shorter than 5'6" and 1/2 Fonzie - I'd say 5'5".

leonari says on 19/Mar/07
X: I agree. But he is at least 5'5"

X says on 19/Mar/07
During his "Days" days, magazines listed him as 5 ft. 4 and sometimes as 5 ft. 4 and a half. During his "Baywatch" days, it was clear that his on-screen girlfriend (portrayed by 5 ft. 6 Erica Eleniak) was at least an inch taller.

IMO, his build puts him closer to 5 ft. 4 than 5 ft. 6.

Gary says on 14/Aug/06
I always figured Billy was not real tall, clear back from his first appearance on Days of our Lives. But at 5'6" or 6'6" he is really good looking