Fuel Mileage Calculator
Calculate fuel economy as km/L, US MPG, and L/100 km from distance and fuel consumed. Choose kilometres or miles, and litres or US gallons.
What Is a Fuel Mileage Calculator?
A fuel mileage calculator converts a trip distance and the amount of fuel used into fuel-economy figures. This tool reports three common measures: kilometres per litre (km/L), US miles per gallon (US MPG), and litres per 100 kilometres (L/100 km). US gallons are used for MPG, not Imperial gallons.
How to Use the Fuel Mileage Calculator
- Enter the distance — Type how far you travelled. Values must be greater than zero.
- Choose the distance unit — Select kilometres or miles. The calculator does not assume a unit.
- Enter the fuel consumed — Type how much fuel was used. Values must be greater than zero.
- Choose the fuel unit — Select litres or US gallons.
- Click Calculate — The tool shows km/L, US MPG, and L/100 km.
Formulas
Distance is converted to kilometres and fuel is converted to litres before km/L is calculated:
- 1 mile = 1.609344 kilometres
- 1 US gallon = 3.785411784 litres
- km/L = distance in kilometres ÷ fuel in litres
- US MPG = km/L × (3.785411784 ÷ 1.609344)
- L/100 km = 100 ÷ km/L
Practical Uses
- Trip logs: Compare fuel use after a fill-up
- Vehicle comparison: Convert between metric and US economy figures
- Cost planning: Estimate how far a tank should last
Examples
- Example 1: 100 km using 8 L → 12.500 km/L, 29.402 US MPG, 8.000 L/100 km
- Example 2: 100 miles using 4 US gallons → 10.629 km/L, 25.000 US MPG, 9.409 L/100 km
Frequently Asked Questions
Does this calculator use US gallons or Imperial gallons?
US gallons only. One US gallon is 3.785411784 litres. Imperial gallons are not supported, so the MPG result is labelled US MPG.
Can I mix kilometres with US gallons?
Yes. The calculator converts distance to kilometres and fuel to litres first, then computes km/L, US MPG, and L/100 km from those values.
Why are zero or negative values rejected?
Fuel economy is distance divided by fuel. Zero or negative distance or fuel would produce invalid or infinite results, so the tool asks for positive numbers instead.
Is this fuel mileage calculator free?
Yes. It runs in your browser with no registration required.