Fuel Cost Calculator
Fuel economy in Australia is measured in litres per 100 kilometres (L/100km), lower is better. The calculation is straightforward: litres used divided by distance driven, multiplied by 100. Australian fuel prices vary by state, day of the week, and retailer, typically ranging 150–220 cents/litre for ULP91 as of 2025. The weekly fuel price cycle (lowest Tuesday or Wednesday, highest Thursday or Friday in Sydney and Melbourne) means timing your fill-up can save –15 on a 60-litre tank. This calculator works out cost per trip, cost per 100 km, litres needed for a journey, and annual fuel spend based on your driving pattern. It supports ULP91, ULP95, ULP98, diesel, and LPG, and lets you compare two vehicles side by side. Useful for estimating road trip costs and working out whether a more fuel-efficient car justifies its price premium.
Frequently Asked Questions
How is fuel economy calculated?
In Australia, fuel economy is measured in litres per 100km (L/100km). The formula is (Litres used divided by Kilometres travelled) multiplied by 100. A lower number means better fuel efficiency. For example, using 8.5 litres to travel 100km equals 8.5 L/100km. The average new car in Australia uses about 8-9 L/100km, though this varies significantly between vehicle types. Enter your distance travelled and fuel used to calculate your actual consumption.
What affects my actual fuel consumption?
Driving style has the biggest impact: rapid acceleration and heavy braking can increase fuel use by 30-40%. Speed matters significantly too, with optimal economy typically around 70-80 km/h on highways. Other factors include tyre pressure (under-inflated tyres increase rolling resistance and fuel use), air conditioning use (can add 10-20%), vehicle load (extra weight increases consumption), road conditions (hills, traffic congestion), and whether you're using 4WD or have roof racks attached. Keeping your tyres properly inflated is one of the easiest ways to improve efficiency.
What's the difference between mpg and L/100km?
Miles per gallon (mpg) measures how many miles you can travel on one gallon of fuel, where higher is better. Litres per 100km (L/100km) measures how many litres you use per 100km travelled, where lower is better. They are inversely related. UK mpg and US mpg are different measurements due to different gallon sizes. Most countries outside the US use L/100km as the standard measure. If your car uses 8 L/100km, that's approximately 35 mpg (UK) or 29 mpg (US) for comparison purposes.
How can I improve my fuel efficiency?
Drive smoothly at moderate speeds (70-80 km/h on highways is often the efficiency sweet spot for most vehicles), maintain correct tyre pressure (check monthly and before long trips), reduce unnecessary weight (remove roof racks when not in use), plan routes to avoid heavy traffic, use air conditioning sparingly, switch to synthetic engine oil (reduces internal friction), and keep your car serviced with clean air filters. Hypermiling techniques like anticipating traffic conditions can improve economy by 15-20% without any mechanical changes to your vehicle.
Why do I get different fuel consumption to the label?
The fuel consumption label is based on laboratory tests (similar to the US EPA and EU test cycles) under controlled conditions: 25 degrees Celsius, no accessories, no climate control, on a dynamometer simulating flat roads at constant speeds. Real-world driving includes cold starts, air conditioning use, varying speeds, hills, passenger and luggage weight, traffic stops, and aerodynamic drag at highway speeds. Studies consistently show real-world consumption is 20-40% higher than the label figure regardless of country. Your actual consumption will vary depending on your specific driving patterns and conditions.
How much does speeding affect fuel consumption?
Fuel consumption increases significantly at higher speeds due to aerodynamic drag, which increases with the square of speed. At 100 km/h versus 80 km/h, you typically use 10-15% more fuel. At 110 km/h versus 100 km/h, consumption increases another 10-15%. At 130 km/h, a car may need 30-40% more fuel to overcome air resistance than at 80 km/h. The optimal highway speed for most modern cars is around 70 km/h. Maintaining a steady speed rather than constant acceleration and braking also significantly reduces consumption.