1) The imperial gallon: The imperial gallon can be defined in terms of liter. One imperial gallon is approximate equals to 4.55 L (liter). Imperial gallon is actually defined on basis of volume of ten pounds of water at 17 °F. One of the terms is imperial fluid ounce. Imperial fluid ounce can be defined as 1 / 160 of an imperial gallon.
2) US liquid gallon: US liquid gallon can be defined as 231 (inches) 3. US liquid gallon is equals to exactly 3.785412 liters. Since 3.785412 liter is approximate equals to 0.13368 (feet) 3 and hence we can say that US liquid gallon is approximately equals to 0.13368 cubic feet or (feet) 3. Another term is US fluid ounce which can be defined as 1 / 128 of a US liquid gallon.
3) US dry gallon: US dry gallon is actually one – eighth of 2150.42 (inches) 3. Thus US dry gallon can be defined as gallon equals to exactly 4.40488377086 liter or 268.8025 (inches) 3.
Gram (symbol ‘g’) can be defined as unit of mass. In other words, gram can be described as "absolute weight of a volume of pure water equals to (the hundredth part of a meter) 3 and at temperature of melting ice. Gram can also be defined as 1 / 1000 of kilogram (10 -3 kg). Symbol for gram is "g" which is fixed by SI unit system.
Gallons are used to measure volume whereas grams are used to measure mass (weight). A gallon is approximately equals to 3780 gram.