The cubic foot is a unit of volume in the imperial unit system with the symbol ft³.
1 cubic foot is equal to 1/27 yd³ or 1728 in³. It is equal to the volume of a cube measuring 1ft on each side.
One cubic foot of water weighs 62.4 lbs or 28.29 kg.
The liquid gallon is a unit of volume in the US customary unit system and uses the symbol gal.
It is the most common use of the word gallon and is defined as 231 in³. It is made up of 4 quarts where there are 2 pints in a quart and 16 US fluid ounces in a US pint. There are therefore 128 US fluid ounces in a US gallon.
The term gallon is most prevalent when discussing and trading oil and fuel. To ensure consistency, the temperature of the liquid (typically petroleum or alcohol) is understood to be 15.6 °C (60 °F) at the time of measurement.