Fuel Economy Converter

Fuel economy measures how far a vehicle can travel on a specific amount of fuel, expressed as distance per unit volume. In the United States, the most common unit is miles per US gallon (MPG), while most other countries use liters per 100 kilometers (L/100km) or kilometers per liter (km/L). It is important to note that the US gallon (3.785 liters) and the Imperial gallon used in the UK (4.546 liters) are different, so MPG figures are not directly comparable across the Atlantic without conversion.

For electric and alternative-fuel vehicles, the EPA introduced miles per gallon gasoline equivalent (MPGe) to provide a familiar efficiency metric. MPGe represents the distance a vehicle can travel using the same amount of energy contained in one gallon of gasoline—roughly 33.7 kilowatt-hours of electricity. You can learn more from Wikipedia's article on fuel economy in automobiles and miles per gallon gasoline equivalent.

Converting between systems is straightforward with the right constants. One US MPG equals approximately 1.201 Imperial MPG, and one Imperial MPG equals about 0.8327 US MPG. To move between MPG (US) and L/100km, use the formula 235.215 ÷ MPG = L/100km. For example, 25 MPG (US) is roughly 9.4 L/100km, while 50 MPG (US) is about 4.7 L/100km.

Electric vehicles often achieve impressive MPGe ratings: a typical modern EV may score between 100 and 130 MPGe, reflecting the high efficiency of electric drivetrains compared to internal combustion engines. Understanding these equivalents helps when comparing a hybrid, plug-in hybrid, or fully electric vehicle against a conventional gasoline car.

Fuel economy conversions are essential when shopping for cars across international markets. A European brochure listing 6 L/100km translates to roughly 39 MPG (US), which is useful context for an American buyer evaluating an imported model. Fleet managers also rely on consistent units to normalize fuel consumption data across vehicles from different regions and to calculate total cost of ownership.

Government regulations such as the US Corporate Average Fuel Economy (CAFE) standards mandate minimum fleet-wide efficiency, pushing manufacturers to develop lighter materials, aerodynamic designs, and electrified powertrains. Meanwhile, EPA test cycles provide standardized ratings that consumers see on window stickers, even though real-world driving habits—speed, traffic, weather, and maintenance—often produce different results. Using this converter, you can translate any rating you encounter into the unit you understand best.