What is trip fuel planning?

Before a drive, it helps to know how much fuel it will take. The answer depends on how far you go and how much fuel your car uses per distance. Carmakers state that consumption in different ways: liters per 100 kilometers in most of the world, kilometers per liter in some countries, and miles per gallon in the United States and the United Kingdom, where the two gallons are not the same size. A US gallon is 3.785 liters, and a UK gallon is 4.546 liters.

Tool description

This calculator works out how much fuel your car needs for a trip. Enter the distance and your car's consumption, in any of the four common units, and the tool shows the fuel you need. Add the fuel price to get the trip cost and the cost per kilometer or mile. Add the size of your tank to see how far a full tank goes and how many times you have to stop to refuel. A scale under the results shows how high or low your fuel usage is compared with an average car. Everything is calculated in your browser.

Examples

Trip Consumption Fuel price Fuel needed Trip cost Tank Refuel stops
500 km 7.5 L/100 km 1.60 per L 37.5 L 60.00 45 L 0
300 mi 30 MPG (US) 3.50 per gal 10 gal (US) 35.00 14 gal 0
250 mi round trip (500 mi) 40 MPG (UK) 6.50 per gal 12.5 gal (UK) 81.25 10 gal 1
1,200 km 12 L/100 km 1.60 per L 144 L 230.40 70 L 2

Features

  • Consumption in L/100 km, km/L, MPG (US), or MPG (UK), with the distance in kilometers or miles
  • Trip cost and cost per distance for any currency, with an option to count the drive back
  • A colored scale that shows whether your fuel usage is low, average, or high

How it works

The tool first turns your consumption into liters per kilometer, which makes every unit comparable:

  • L/100 km: divide by 100.
  • km/L: take 1 divided by the value.
  • MPG: divide the size of the gallon in liters (3.785 for US, 4.546 for UK) by the value times 1.609344, the number of kilometers in a mile.

The fuel for the trip is the distance in kilometers times that number, converted to the unit that goes with your consumption: liters, US gallons, or UK gallons. The cost is the fuel times the price of one unit. The range of a full tank is the tank size divided by the liters per kilometer, and the refuel stops are the number of tanks the trip needs, minus the full tank you start with.

The usage scale covers about 2 to 14 L/100 km, which is 6 to 20 km/L, 12 to 48 MPG (US), or 14 to 58 MPG (UK). The middle of the scale is around 8 L/100 km, or 30 MPG (US), which is typical for a family car. For km/L and MPG the high usage end is on the left, because a bigger number means less fuel.

Tips

  • When you switch the consumption unit, the tool converts your consumption, the fuel price, and the tank size, so they keep describing the same car and fuel
  • Use the consumption from your trip computer or from your last few tank fills rather than the figure in the brochure, which is measured in test conditions and is usually lower than real driving
  • Real use goes up at motorway speeds, with a roof box or a heavy load, in cold weather, with the air conditioning on, and in stop-and-go traffic. Adding 10 to 15% is a safe margin for a long trip
  • The refuel stops assume that you start with a full tank and refuel only when it is empty. In practice, you will want to stop before the tank runs dry
  • Diesel, petrol, and gasoline all work in the same way, since only your car's consumption matters. This tool does not cover electric cars, for which use the EV Trip Charging Calculator