To estimate the fuel cost for a trip you must know the trip distance, the average per litre cost of fuel and the vehicle’s fuel consumption. 

The process is as follows. 
  • Divide the trip distance by 100. 
  • Multiply the result of this by the fuel consumption. 
  • Then multiply this figure by the cost of fuel/litre.


Step 1. 815 km divided by 100 = 8.15.
Step 2. 8.15 multiplied by 9 (litres per 100km) = 73.35.
Step 3. 73.35 multiplied by $1.50 (per litre) = $110.

You will need to substitute the figures that relate to your trip and vehicle. 

If you don’t know your vehicle’s fuel consumption an approximate figure can be found on the following web sites. For current models visit

We suggest using the Combined Consumption figure for your calculations. 

For older vehicles visit We suggest using an average of the city and highway figures.

Additional notes and resources

  • Factors affecting fuel consumption include vehicle load and condition, road and traffic conditions and driving style. Actual consumption could be higher or lower than the figures suggested by these sites. 
  • The figures provided by these sites will not be accurate for vehicles carrying heavy loads or towing heavy trailers or caravans etc. In such cases the only way to determine the likely fuel consumption with any certainty is actual experience. 
  • Winds can have a huge impact on fuel consumption, particularly when towing caravans. 
  • The method provided above is primarily for estimating highway fuel costs. If a city trip cost needs to be estimated, substitute a city fuel consumption figure for the highway consumption. 
  • If an estimate of cost for a combination city / highway is required, it will be necessary to calculate each component separately and total the results. 
  • Trip distance can be found at RACQ Trip Planner
  • Fuel cost i.e. cost /litre, can be difficult to determine as it is dependent on where you fill up. However, Fuel Prices may be of assistance.


  • This method will provide a reasonable indication of trip fuel costs. 
  • If you must produce a reasonably accurate estimate for a trip that involves numerous fills where the fuel cost is likely to vary significantly, i.e. city prices Vs country prices, it is necessary to do the calculations for each leg of the trip and factor in the fuel cost of each fill. 
  • Note however that even when doing this there could be significant variations due to road, traffic and weather conditions, and unexpected changes in fuel prices.