RACQ Motoring

Estimating the cost of fuel for a trip

o estimate the fuel cost for a trip you will need to know the trip distance, the average per litre cost of fuel and the vehicle’s fuel consumption in litres / 100km.

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 particular 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 models built after 2003 see; Australian Government Green Vehicle Guide Website we would suggest using the Combined Consumption figure for your calculations.

For vehicles built between 1986 and 2003 refer to; Australian Government Fuel Consumption Website we would suggest using an average of the city and highway figures.


  • The actual fuel consumption will be affected by factors such as vehicle load and condition, road and traffic conditions and driving style and 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 of determining the likely fuel consumption for a particular tow vehicle / trailer combination with any certainty is actual experience. Note also that 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 will depend on where you fill up. However this link Fuel Prices may be of assistance.


The method given above will provide a reasonable indication of trip fuel costs. The more accurate the information, the more accurate the result will be. However if your trip will involve numerous fills where the fuel cost is likely to vary significantly, i.e. city prices Vs country prices, and it is necessary to produce a reasonably accurate estimate, it would be necessary to do the calculations for each leg of the trip and factor in the fuel costs 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.

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The information provided in this fact sheet is intended as a general guide only. You should carry out further research and investigations into the topics outlined above prior to implementing any actions or recommendations