Gallons to Litres: The Complete Guide
Gallons come in two distinct sizes. The US liquid gallon (3.785 litres) is used in the United States. The Imperial gallon (4.546 litres) was used in the UK and is still used in some Commonwealth countries. Always clarify which type you're working with.
The Conversion Formulas
litres = US gallons × 3.785
litres = Imperial gallons × 4.546Quick Reference Table
- 1 US gal = 3.785 L
- 1 UK/Imperial gal = 4.546 L
- 5 US gal = 18.93 L
- 10 US gal = 37.85 L
- 55 US gal = 208.2 L (standard drum)
The 20% Difference Matters
A US gallon is about 17% smaller than an Imperial gallon. This is why fuel economy figures vary so much between US and UK car reviews — a car achieving 50 MPG (Imperial) only achieves about 42 MPG in US measurements, even though it's the exact same car.
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Complete Reference Table (US Gallons)
- 1 US gal = 3.785 L
- 2 US gal = 7.571 L
- 5 US gal = 18.927 L
- 10 US gal = 37.854 L
- 20 US gal = 75.708 L
- 50 US gal = 189.271 L
- 1 UK gal = 4.546 L
- 10 UK gal = 45.461 L
US Gallon vs UK (Imperial) Gallon
The most common source of error with gallons is the two different definitions. The US liquid gallon (3.785 L) is the standard in the United States for fuel, beverages, and household liquids. The Imperial gallon (4.546 L) is the standard in the United Kingdom, Canada (historically), and some Caribbean nations. The Imperial gallon is about 20% larger. This distinction matters enormously when comparing fuel economy: a car achieving 30 mpg on the UK gallon achieves the equivalent of only about 25 US mpg. Always confirm which gallon is being used before making calculations involving fuel, water storage, or large-volume containers.
Common Applications
- Fuel economy: US cars advertise economy in miles per US gallon; European comparisons use litres per 100 km.
- Aquariums: Tank sizes are often listed in US gallons; filtration and dosing instructions may use litres.
- Water storage tanks: Agricultural and industrial tanks are often rated in US gallons in North America.
- Cooking and brewing: US recipes use cups and gallons; converting to litres is common for brewing larger batches.
Frequently Asked Questions
How many gallons are in a litre?
One litre equals 0.2642 US gallons or 0.2200 Imperial gallons. Inversely, 1 US gallon = 3.7854 litres and 1 Imperial gallon = 4.5461 litres.
Which gallon does Canada use?
Canada officially uses litres for all fuel and liquid measurements under the metric system. Although Imperial gallons were historically used, Canada metricated in the 1970s and 1980s. Canadian gas stations display prices per litre, not per gallon.
Is a US gallon the same as a dry gallon?
No. The US also has a dry gallon (4.405 L), used historically for grain and produce, but it is rarely encountered today. When people say "gallon" in the US, they almost always mean the liquid gallon (3.785 L).