Calc4Living

Automotive Costs · Free calculator

MPG Calculator

Calculate measured fuel economy from distance traveled and fuel consumed, with US and imperial MPG clearly separated.

Your vehicle and journey inputs

Prefilled measurements are editable examples. Prices and rates start at zero: unpriced, not local quotes. All fields are required unless marked optional. Results clear when inputs change. Unit changes convert current values; currency changes preserve numbers without exchange rates.

Enter the distance traveled.

Fuel actually consumed over the measured distance; zero gives undetermined economy.

Your estimate

Measured fuel economy

Review the editable example values, enter your own prices where needed, then calculate.

How do I calculate MPG from distance and fuel used?

km/L = distance in kilometers ÷ fuel in liters. US MPG = km/L × 3.785411784 ÷ 1.609344. Imperial MPG = km/L × 4.54609 ÷ 1.609344. L/100 km = liters ÷ kilometers × 100.

Worked example

Traveling 100 km using 8 L gives 12.5 km/L, 8 L/100 km, about 29.4018 US MPG and 35.3101 imperial MPG.

Unit conversions

1 mile = 1.609344 km. 1 US gallon = 3.785411784 L. 1 imperial gallon = 4.54609 L. US MPG and imperial MPG use different gallon volumes. kW measures power; kWh measures energy.

Assumptions & limitations

  • Use fuel actually consumed over the same measured distance. Consistent fill-to-fill measurements are more useful than a single inaccurate gauge reading.
  • Zero fuel makes all economy values undetermined; the tool never presents infinite MPG. With positive fuel but zero distance, MPG and km/L are 0 while L/100 km is undetermined.
  • US gallons are 3.785411784 L; imperial gallons are 4.54609 L. A gallon must always have its system specified.