Hi ICANT,
Your hand being 4 and 1/8 inch across is very 'handy' isn't it, however this is not the size of a handsbreadth in the Bible.
A handsbreadth is around 3 inches.
As we know a cubit is 18 inches, a handsbreadth was a 1/6 of a cubit, therefore it would be 3 inches ( Scott, R. B. Y. (1958)
The Hebrew Cubit Journal of Biblical Literature, Vol. 77, No. 3 (Sep., 1958), pp. 205-214, ref page 213.
Even a quick look at some online Bibles support this.
An
online NIV 1 Kings 7:26
It was a handbreadth [q] in thickness, and its rim was like the rim of a cup, like a lily blossom. It held two thousand baths.
The footnote for [q] says
"That is, about 3 inches (about 8 centimeters) "
Another interesting snippet in Scott's article is that there is conflicting versions of 1 Kings 7.
On page 209 he tells us that the LXX says the circumference was 33 cubits, in disagreement with the 30 cubits of the MT, and contradicting itself with the parallel passage in 2 Chron. 4.
The MT contradicts itself in regard to the capacity, 1 Kings stating 2000 baths and 2 Chron. stating 3000. The LXX doesn't give the capacity at 1 Kings but states 3000 at 2 Chron.