What is the difference between UK and US gallons?

A UK (imperial) gallon is 4.54609 litres while a US gallon is only 3.78541 litres. The UK gallon is about 20% larger. This matters when comparing fuel economy or tank sizes between UK and American sources.

Why does the UK sell fuel in litres but measure economy in MPG?

The UK metricated fuel sales in the 1990s, switching pumps from gallons to litres. However, road distances remained in miles, so fuel economy is still commonly expressed as miles per gallon. This means UK drivers need to convert between the two systems regularly.

How many litres are in a UK gallon?

One UK (imperial) gallon equals exactly 4.54609 litres. For a quick estimate, multiply UK gallons by 4.5 to get approximate litres.

Why is the UK gallon different from the US gallon?

The UK imperial gallon (4.546 litres) is based on the volume of 10 pounds of water, while the US gallon (3.785 litres) is based on the older English wine gallon. The difference means UK MPG figures are about 20% higher than US MPG for the same consumption.

Which gallon does my car use?

In the UK, fuel economy is quoted in UK (imperial) gallons, giving higher MPG numbers. US cars and websites use the smaller US gallon. If comparing figures from different countries, always check which gallon is being used. This converter handles both.

CarCalcs

Litres to Gallons Converter

Convert between litres and UK or US gallons.

Conversion Direction

Volume (litres)

How We Calculate This

This converter handles both UK imperial gallons and US gallons, showing all three units simultaneously.

The Formulas

Litres to UK gallons: UK gallons = Litres / 4.54609
Litres to US gallons: US gallons = Litres / 3.78541
UK gallons to litres: Litres = UK gallons x 4.54609
US gallons to litres: Litres = US gallons x 3.78541

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Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.