Car & Vehicle

Fuel Required Calculator

How many litres a journey needs, from the distance and your mileage. No price required.

6 inputs Free, no sign-up

Your figures

Use the figure you actually get, not the showroom one. City driving commonly lands 20-30% below a rated number, and the mileage calculator works yours out from a tank.

Tick to count the journey twice.

Try an example

Result

Your result

Enter your figures and the result appears here.

Estimates only. Rates, fees and specifications change. Confirm against the official source before you rely on a figure — see our disclaimer.

About this calculator

How much fuel a trip takes is the distance divided by the mileage. That is the whole calculation, and it is the one you want at the pump when the question is how much to put in rather than what it will cost.

Enter the distance in kilometres or miles and your mileage in any of the four common units. The answer comes back in litres, and in US gallons for anything quoted that way.

How to use this calculator

  1. Enter the distance you are covering.
  2. Enter the mileage you actually get, and pick its unit.
  3. Tick "there and back" if you are returning the same way.
  4. Read the litres.

To turn that into money, use the fuel cost calculator, which takes the same figures and a pump price.

The formula

Fuel needed = Distance / Mileage

Both sides have to be in matching units before the division, which is what the unit selectors are for. A distance in miles is converted at exactly 1.609344 km per mile; a mileage in L/100 km is turned into km/L by dividing 100 by it, which is a reciprocal rather than a scale factor.

SymbolMeaningUnit
Distance Length of the journey km or mi
Mileage Distance covered per litre km/L, L/100 km or mpg

Worked example

A 500 km run at 20 km/L:

Fuel needed = 500 / 20 = 25 litres

There and back, 50 litres — which on most cars is more than one tank, so the trip needs a stop whether or not you planned one.

Notes and limits

  • This is the fuel the distance consumes, not the amount to put in. Nobody runs a tank to empty, and a fuel pump is cooled by the fuel around it, so arriving on fumes is hard on the car as well as on the nerves.
  • Highway mileage is usually well above city mileage. For a long trip, use the highway figure you have actually seen rather than your overall average.
  • A roof box, a full load or a headwind moves the answer by more than most people expect.
  • To find out whether the tank you have will cover it, use the fuel tank range calculator.

What this calculation assumes

  • Mileage is constant over the whole journey.
  • No reserve or margin is added. The figure is what the distance consumes.

Frequently asked questions

How much fuel do I need for 500 km?

Divide 500 by your mileage in km/L. At 20 km/L that is 25 litres; at 12 km/L it is 41.7 litres. The mileage is the figure that decides it, so use the one you actually get.

Should I add a margin?

Yes, in practice. This calculation gives the fuel the distance consumes with nothing spare. Detours, traffic and a reserve you would rather not dip into are all on top, and none of them is assumed here.

Can I use this for a motorcycle?

Yes. The arithmetic is identical - enter the bike's mileage instead. The bike mileage calculator measures it from a tank if you do not know it.

Related calculators