How Many Liters in a Gallon? The Complete Guide (US & UK)

The question "How many liters in a gallon?" is one of the most common conversion queries online. But the answer isn't always straightforward because there are two different types of gallons used around the world.

US Gallon vs UK Imperial Gallon

The United States uses the US gallon (3.78541 L), while the United Kingdom and many Commonwealth countries use the imperial gallon (4.54609 L). This difference dates back to historical measurement standards.

Quick Answer: Liters per Gallon

1 US gallon = 3.785 liters
1 UK (imperial) gallon = 4.546 liters

This means the UK gallon is about 20% larger than the US gallon — a critical difference when comparing fuel economy, cooking recipes, or any liquid measurements.

Gallon to Liter Conversion Table

1 gal (US) = 3.785 L | 1 gal (UK) = 4.546 L
2 gal (US) = 7.571 L | 2 gal (UK) = 9.092 L
5 gal (US) = 18.927 L | 5 gal (UK) = 22.730 L
10 gal (US) = 37.854 L | 10 gal (UK) = 45.461 L

How to Convert Gallons to Liters

To convert US gallons to liters: multiply by 3.785. To convert UK gallons to liters: multiply by 4.546. Going the other way? Divide liters by 3.785 (US) or 4.546 (UK). Use our free volume converter above for instant, accurate results.

Why Knowing the Difference Matters

Using the wrong gallon type can lead to significant errors. For example, if a UK recipe calls for 5 imperial gallons of water and you mistakenly use US gallons, you would be off by nearly 4 liters. This is especially critical in cooking, automotive fuel calculations, and industrial chemical mixing.