A fuel consumption calculator computes your vehicle's fuel economy from the amount of fuel used and the distance travelled. It returns results in all common fuel economy units: litres per 100 kilometres (L/100km), kilometres per litre (km/L), US miles per gallon (MPG) and UK miles per gallon (MPG). These are the same measurement expressed in different ways.

1. Fill your tank completely.
2. Drive a known distance and note the odometer reading.
3. Refill the tank and note the litres added.
4. Enter the litres used and distance driven.
5. Click Calculate.

40 litres used over 500 km:
L/100km: 8.0 | km/L: 12.5 | US MPG: 29.4 | UK MPG: 35.3

Lower L/100km = better fuel economy. Higher MPG = better fuel economy. These are inversely related — a car that uses 5 L/100km is more efficient than one that uses 10 L/100km. US and UK gallons are different sizes, which is why US MPG and UK MPG differ for the same vehicle.

• Not filling the tank completely at both the start and end of the measurement — partial fills produce inaccurate results.
• Confusing US and UK MPG — UK gallons are larger, so UK MPG is always higher than US MPG for the same vehicle.

What is a good fuel consumption figure?

For a modern petrol car: 6–8 L/100km is good; under 6 L/100km is excellent. Diesel cars typically achieve 4–6 L/100km. Hybrids and EVs have much lower or zero fuel consumption.

Why are US and UK MPG different?

A US gallon = 3.785 litres. A UK (imperial) gallon = 4.546 litres. The same vehicle will show a higher MPG figure in UK units because the gallon is larger.