This article is from the Bee Gees FAQ, by David Garcia firstname.lastname@example.org with numerous contributions by others.
I was surprised to discover how hard it's been to get an
answer to this one! Even the "official" reports have changed
over the years, and differ substantially from guesses hazarded by
fans who have met them and posed for photos with them. I was
hopeful that the Official Bee Gees Web Experience would settle
the matter once and for all, but now I see that they use the very
same estimates that I've always been using. Good heavens,
doesn't SOMEBODY have a tape measure over there? Anyway, fans
estimates have been as follows:
Barry: between 5' 10" and 6' 1"
Robin: between 5' 8" and 5' 11"
Maurice: between 5' 6" and 5' 9"
Further, it is interesting to note that the Official Bee
Gees Web Experience lists Andy as having been between 5' 7" and
5' 9" in height.