A gallon (gal) is a unit of volume and capacity in the U.S. customary and imperial systems of measurement. In terms of liters (L):

1 US gallon = 3.785411784 L

1 imperial gallon = 4.54609 L

In the US, there is also a measurement for a dry gallon.

1 US dry gallon = 4.40488377087 L

In both systems of measurement, the gallon can be further divided into smaller units of volume. Their exact values in terms of liters vary based on the definition of the gallon being used, but the division is as follows:

1 gallon  =  4 quarts
   =  8 pints
   =  16 cups
   =  32 gills

The US and imperial systems of measurement are further differentiated into different definitions of fluid ounces.

1 US fluid ounce = pints = gallons

1 imperial fluid ounce = pints = gallons

US and imperial fluid ounces are often used interchangeably since their sizes are relatively similar, but the other measurements mentioned above differ too significantly to be used interchangeably.

Did you know?

One of the most common everyday uses of the gallon in certain parts of the world, such as the US, is its use for the measurement of gasoline. Gasoline is often sold in terms of cost per gallon (or cost per liter in other parts of the world) in bulk through a gasoline pump, or sometimes in smaller amounts in containers. Below is an example of a gasoline can, sold in various measures of a gallon, often between 1.5-5 gallons.