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.
The register ton is a unit of volume in the shipping world and uses the symbol GRT.
1 register ton is equal to 100 ft³ or 2.832 m³.
The register ton is used in shipping to measure the amount of cargo on a vessel. The phrase is often mistaken for a unit of mass or weight because of the term 'ton' but should not be confused.