Fuel Efficiency – Volume Converter

Convert between mpg, km/L, and L/100km, the everyday volume-based fuel efficiency units used for cars and road vehicles.

The Everyday Fuel Efficiency Units Explained Properly

Volume-based fuel efficiency, the figures printed on every car’s window sticker and fuel economy label, compares distance travelled against a fixed volume of fuel consumed, and exists in two fundamentally different framings depending on which country’s convention is being used. Miles per gallon and kilometres per litre both express fuel economy the same direction, distance achieved per unit of fuel, meaning a higher number always represents better efficiency in both units, and converting between them is a single, direct ratio combining the underlying distance and volume conversions already covered separately. Litres per hundred kilometres inverts this entirely, expressing fuel consumed per fixed distance rather than distance per fixed fuel, meaning a lower number represents better efficiency instead, which is why converting from a mpg-style figure to a L/100km-style figure genuinely requires dividing into a constant rather than simply multiplying by a ratio, precisely the same inversion covered in more detail under the dedicated fuel consumption converter, and worth double-checking carefully any time a comparison is being made across figures that might be using these two opposite conventions without saying so explicitly.