Cubit is the Primitive unit of length equivalent to a span of the forearm.
The unit based on the length of a forearm was the cubit
China
a cubit is a unit of mesurment from the length of the tip of the middle finger to the elbow.
None, since there can be no conversion. A cubit = 1.5 feet so a cubit foot (= 1.5 square feet) is a measure of area in 2-dimensional space. Energy is measured in terms of BTU per unit of volume or mass, not of area. So "BTU per standard cubit fet" is a nonsense unit.
A cubit and a footstep are a type of archaic unit of length that was mostly used during the Middle Ages. It is not used as a standard unit of length today because they were not proven to be consistant lengths.
The cubit which is about 0.5 metre in modern terms
A foot is a unit of length. A cubic yard is a unit of volume. The two units are therefore incompatible.
"cubit feet" is nonsense; there's no such measurement. "cubic feet" is a valid unit of measurement, but it's a volume measurement and cannot be converted into pounds, a weight measurement.
Your question is very confused. The cubit is a unit of measurement that has nothing to do with inches or feet. Possibly you intended to ask how many cubic inches are in a cubic foot, the answer being 1728.
A cubit is a unit of length equal to the length of a person's forearm from the elbow to the fingertips - about a foot and a half or 18" There are .677 cubits in a foot
it is cubit