Both gallons and liters are units for measuring volume. Gallons are generally used in the US imperial system, while liters in the metric system. However, there are actually different types of gallons. There are liquid gallons, dry gallons, and imperial gallons. Liquid and dry gallons are used in the US and some nations in Latin America, while the imperial gallon is used in the UK and some commonwealth nations. There are 4.54 liters in one imperial gallon, 3.78 liters in one liquid gallon, and 4.4 liters in one dry gallon.

　　

US Gallons: Liquid and Dry

Gallons of fuel with the US flag in the background The United States is well-known for being one of the only nations on Earth that actively uses the imperial system in most measurements. Today, most countries have adopted the metric system due to the simplicity of converting between units. While liters are the standard unit of volume in the metric system, gallons are the standard unit of volume in the imperial system. So it is important to know how to convert between the two units. As stated before, US gallons are divided into two types: liquid gallons and dry gallons. A liquid gallon contains 3.78 liters, while a dry gallon contains 4.4 liters. A dry gallon is defined using the bushel, and one dry gallon is equal to ⅛ of a bushel of grain. 

　　

Imperial Gallon

The UK used the imperial gallon as a unit until 1994 when the UK government officially adopted the liter as the standard unit of volume. The gallon remained a secondary unit of measurement until September 30, 1995, when the government amended legislation in favor of the liter. The imperial gallon is defined as the volume of 4.54kg of water at 17 degrees Celsius, which translates to 4.54 liters.