What is the Gallons to Liters Converter?
This tool converts a volume measured in gallons into liters. Because two different gallons are in common use, the calculator lets you choose between the US liquid gallon and the UK (Imperial) gallon. The US gallon is smaller, so the two answers differ by about 20% for the same number of gallons — always pick the right one.
How to use it
Enter the number of gallons, select whether they are US or UK gallons, and read the result in liters. Decimals are supported, so 2.5 gallons works fine.
The formula explained
The conversion is a simple multiplication by a fixed, exact factor:
US: $$\text{liters} = \text{gallons} \times 3.785411784$$
UK: $$\text{liters} = \text{gallons} \times 4.54609$$
These factors are defined exactly by international agreement, so the conversion has no rounding error beyond the digits you choose to display.
Worked example
How many liters are in 5 US gallons? Multiply $$5 \times 3.785411784 = 18.92705892 \text{ liters}$$ The same 5 UK gallons would be \(5 \times 4.54609 = 22.73045\) liters — noticeably more.
FAQ
Why are there two kinds of gallon? The US kept the old English wine gallon while Britain redefined its gallon in 1824 based on water, producing the larger Imperial gallon.
Which gallon should I use? Use US if your figure comes from the United States; use UK/Imperial for the United Kingdom and some Commonwealth contexts.
Is the factor exact? Yes. \(1 \text{ US gallon} = 3.785411784 \text{ L}\) and \(1 \text{ UK gallon} = 4.54609 \text{ L}\) are exact definitions.
