This is the Hoppus foot rule in metric format with results in Francon cubic metres (fr. M³).

To avoid confusion, the cubic metre result from Hoppus is referred to as a Francon cubic metre.

Formula used:

V = (G ÷ 4)² * L ÷ 10000

V = volume in Francon cubic metres
G = girth measured mid point of the log in centimetres
L = length of log in metres

one Francon cubic metre (fr. M³) = 1.27324 cubic metres (m³)
one Francon cubic metre (fr. M³) = 44.964 cubic feet (ft³)
one Francon cubic metre (fr. M³) = 35.315 Hoppus feet (h ft)