Fuel Consumption Calculator
How much your car really uses, from a fill-up and the distance driven: litres per 100 km, km per litre and miles per gallon.
Runs entirely in your browser. Nothing is uploaded, logged or stored.
Consumption
7.00 L/100 km
- Distance per litre
- 14.29 km/L
- Miles per US gallon
- 33.6
- Miles per imperial gallon
- 40.4
- Cost of the fuel
- Cost per 100 km
Fill the tank to the brim, note the trip counter, and fill it again at the next stop. What went in the second time is what the car used over that distance, and this turns it into every unit consumption is quoted in.
How it works
Litres per hundred kilometres is the fuel divided by the distance, times a hundred. Kilometres per litre is the same ratio the other way up, which is why one goes down when the other goes up.
Miles per gallon is also distance over fuel, so it converts to litres per hundred kilometres by a reciprocal, not a factor. The two gallons differ as well: an imperial gallon is 4.546 litres and a US gallon 3.785, so the same car reads about twenty per cent better in imperial figures.
Give the price you paid and the page adds what the fuel cost and what every hundred kilometres costs at that price. The price is per litre or per gallon, matching the unit the fuel was given in.
Examples
| Case | Input | Result |
|---|---|---|
| A fill-up in litres | 42 L over 600 km | 7.00 L/100 km — 14.29 km/L |
| The same car in miles per gallon | 7 L/100 km | 33.6 US mpg, 40.4 imperial mpg |
| A fill-up in US gallons | 10 US gal over 300 mi | 7.84 L/100 km — 30.0 US mpg |
Frequently asked questions
Why fill the tank to the brim twice?
Because the fuel gauge is not precise enough to measure with. Filling to the same point at both ends means the second fill is exactly what the car burned over the distance in between. A single fill and a guess at what was left can be out by several litres.
Why is my figure higher than the manufacturer's?
The official figure is measured on a standard test cycle, under conditions chosen to be repeatable rather than typical. Short trips, cold starts, motorway speeds and air conditioning all add to it. Your own fill-up figure is the one to plan with.
Does this work for an electric car?
The same division does: kilowatt-hours charged over kilometres driven, times a hundred, is kilowatt-hours per hundred kilometres. This page speaks in litres, so for an electric car use the fuel cost calculator, which takes kWh per 100 km and prices a journey with it.
Good to know
- Average a few fill-ups rather than trusting one: a tank of motorway driving and a tank of town driving can differ a great deal, and the mix of the two is what you actually pay for.