Units of Volume
The unit of length underlies the unit of volume (metre, centimetre, etc.).
The gallon and litre were originally standards of liquid measure but are now formally defined in terms of the cubic metre.
The stere and cord are used exclusively for fuelwood measurement and represent 1 cubic metre and 128 cubic feet of stacked fuelwood, respectively. The actual volume of solid wood in each of the units is, therefore, ill-defined as the density of stacking and shape of the pieces of wood used can vary considerably.
Conversion Equivalents between Units of Volume