A volume in cubic feet can be converted to imperial gallons by dividing by 0.134 or multiplying by 7.462. A gallon is also a metric unit of measurement, but a different volume than an imperial gallon. To convert cubic feet to a metric gallon, multiply the volume by 8.9544.
A foot is an imperial measure of length in one dimension. By using area formulas for various shapes, area can be calculated in feet squared. Area is a two dimensional measurement, while volume is a three dimensional measurement. By integrating depth or height into area equations to derive volume equations, a volume result can be calculated in cubic feet. This can then be converted to gallons.