How to Convert Gallons to Liters
To convert US gallons to liters, multiply the number of gallons by 3.78541. The formula is liters = gallons × 3.78541. The converter above does it instantly. A quick estimate is that a gallon is just under four liters, so multiplying by 4 and trimming a little gets you close.
The Gallons to Liters Formula
One US gallon equals 3.785411784 liters. To convert gallons to liters, multiply by 3.78541; to convert liters back to gallons, divide by the same number. As with fluid ounces, there are two gallons: the US gallon (3.785 L) and the larger UK imperial gallon (4.546 L). This converter uses the US gallon, which is what most searches and US products refer to, so double-check if a figure is explicitly British.
Worked Examples
1 gallon: 3.79 liters. 5 gallons: 18.93 liters. 10 gallons: 37.85 liters. A typical 15-gallon car tank is about 56.8 liters, and a 55-gallon drum is about 208 liters. These conversions come up with fuel, water storage, aquariums, and large containers.
Common Gallon to Liter Values
Quick reference: 1 gal ≈ 3.79 L, 2 gal ≈ 7.57 L, 5 gal ≈ 18.93 L, 10 gal ≈ 37.85 L, and 20 gal ≈ 75.71 L. For a fast estimate, multiply gallons by 3.8; for accuracy with fuel or a recipe, use the converter above. Remember a UK gallon would give a larger result (multiply by 4.546).
Why Convert Gallons to Liters?
Gallons are standard in the United States for fuel, milk, paint, and water, while liters are the metric unit used in most of the world. Converting gallons to liters helps when buying fuel abroad, comparing vehicle tank sizes, following an international recipe, sizing an aquarium or water tank, or understanding a product sold in the other unit. Because the US and imperial gallons differ noticeably, using a precise converter avoids the errors that come from assuming all gallons are the same size.
Gallons, Liters, and Fuel Economy
One of the trickiest related conversions is fuel economy, because the units invert. Miles per gallon (higher is better) and liters per 100 km (lower is better) move in opposite directions, so you cannot simply convert the number — you convert the gallons to liters and the miles to kilometers, then recompute. For straightforward volume, though, gallons to liters is a clean multiply-by-3.785. The converter also supports liters, milliliters, quarts, pints, cups, and more, so any liquid-volume conversion is covered.
US and UK Gallons
The US gallon (3.785 L) and the imperial gallon (4.546 L) differ by about 20%, which is enough to matter for fuel costs and large volumes. The imperial gallon is still used in some contexts in the UK and a few other countries. If a figure is explicitly imperial, multiply by 4.546 instead of 3.785. For the common US case — American cars, recipes, and products — the 3.78541 factor used here is correct, and it keeps even large tank and drum volumes accurate.
Frequently Asked Questions
How many liters in a gallon?
One US gallon is about 3.785 liters; one UK gallon is about 4.546 liters.
How do I convert gallons to liters?
Multiply the US gallons by 3.78541. For example, 5 gallons = 18.93 liters.
How many liters is 5 gallons?
5 US gallons is about 18.93 liters.
Gallons and Liters in Everyday Life
In the United States, gallons are everywhere: fuel at the pump, milk and water by the jug, paint by the can, and aquariums by capacity. Travel or shop internationally, though, and those same things are sold by the liter, so converting bridges the gap. A 1-gallon jug of milk is about 3.8 liters; a 5-gallon water bottle is roughly 19 liters; and a can of paint that covers a room might be 1 gallon (3.8 L) or sold abroad as a 4-liter tin. Fuel is the most common conversion of all — filling a 14-gallon tank means pumping about 53 liters, which is useful to know when prices abroad are posted per liter. Sizing an aquarium or a rain barrel also calls for this conversion, since tank capacities and stocking guidelines may be given in either unit. The exact 3.785 factor keeps all of these everyday volumes accurate.