The unit used to express volume is the cubic meter. This is the SI unit for the volume of a solid, gas or liquid. Volume is also expressed in units like liter, gallon, quart, pint, fluid ounce and cup.
In the U.S., two measurement systems, the U.S. System and the metric system, are used. The SI system, which was introduced for worldwide standardized measurements, is based on the metric system. Gallon, quart, pint, fluid ounce and cup are part of the U.S. System. One gallon is equivalent to 4 quarts, while 1 quart is equivalent to 2 pints. One pint is equivalent to 16 fluid ounces. Liter is part of the metric system. One liter is equivalent to 1 cubic deciliter.