Liters to Gallons Converter

Converting litres to gallons requires knowing which gallon is meant, because there are two in common use and they differ by about twenty per cent. The US liquid gallon is 3.785411784 litres, while the imperial gallon used in the United Kingdom and some Commonwealth countries is 4.54609 litres. This converter uses the US gallon, which is the more widely encountered of the two internationally.

That difference is not a trivial rounding matter. A twenty per cent discrepancy in a fuel calculation, a tank capacity, or a chemical dilution is large enough to cause real problems, and because both units are simply called 'gallons' in everyday speech the mistake is easy to make. The divergence is historical: the US retained the older English wine gallon of 231 cubic inches, while Britain redefined its gallon in 1824 based on the volume of ten pounds of water, creating two units with the same name and different sizes.

Fuel economy is where the confusion causes the most visible trouble. A car rated at thirty miles per gallon in the US is achieving a different real efficiency than one rated at thirty miles per gallon in the UK, because the UK figure is based on a larger gallon — it corresponds to roughly twenty-five US miles per gallon. Comparing published fuel economy figures across the Atlantic without accounting for this makes British cars look substantially more efficient than they are.

Most of the world avoids the problem entirely by using litres for fuel and litres per hundred kilometres for efficiency. That measure also runs in the opposite direction to miles per gallon: a lower number is better, since it counts fuel consumed per distance rather than distance achieved per fuel.