How do you convert gallons to liters?

There are 4.54609 litres in an imperial (UK) gallon and 3.78541 litres in a US liquid gallon and 4.40488 litres in a US dry gallon. To convert litres to any particular unit, multiply the number of gallons by the number of litres in that particular "flavor" of gallon to get your answer.
One Gallon is 3.7854118 litres.
For US measure, gallons x 3.785 = liters