Convert between MPG (US), MPG (Imperial), L/100km, and km/L with formulas
This fuel economy converter supports four common units: Miles per Gallon (US), Miles per Gallon (Imperial/UK), Liters per 100 kilometers (L/100km), and Kilometers per Liter (km/L). It converts between all units and displays the formulas used for each conversion direction, making it both a calculator and a learning tool.
Select the fuel economy unit you have, enter the value, and click "Convert". The results show the equivalent fuel economy in all units along with the formulas used. For example, enter 25 MPG (US) to see it equals about 9.41 L/100km or 10.6 km/L. The formula section explains how each conversion is performed.
A US gallon equals 3.785 liters, while an Imperial (UK) gallon equals 4.546 liters — about 20% larger. This means MPG (Imp) values are always higher than MPG (US) for the same fuel efficiency. For example, 30 MPG (US) ≈ 36 MPG (Imp).
Most countries outside the US, UK, and a few others use the metric system and express fuel consumption as liters per 100 kilometers. Unlike MPG (where higher is better), L/100km is a consumption measure where lower is better. This is the standard in Europe, Canada, Australia, and most of Asia and South America.