A worked example
Sarah lives in Newcastle and is planning a road trip to Byron Bay, a distance of 220 kilometres. Her 2019 Toyota Corolla uses 6.5 litres per 100 kilometres, and she's just checked that petrol at her local servo is $1.89 per litre.
First, she works out her total fuel consumption: 220 km ÷ 100 = 2.2, then 2.2 × 6.5 litres = 14.3 litres for the trip.
Next, she calculates the cost: 14.3 litres × $1.89 = $27.03 for the one-way journey.
If she's driving return, that's 440 kilometres total, which means 28.6 litres and $54.06 in fuel costs. She can also see her cost per kilometre is about 12.3 cents, which helps her compare against the ATO rate of 88 cents per kilometre (which includes all running costs, not just fuel). Sarah now knows fuel is only part of her true driving cost, but for budgeting this weekend trip, the $54 figure is what matters.
State-by-state differences
- NSW: Petrol prices in Sydney typically run 10-20 cents higher than regional areas due to demand and competition. The fuel price cycle averages 4-6 weeks, so timing your fill matters.
- VIC: Melbourne has a similar price cycle to Sydney. Regional Victoria often has cheaper fuel than regional NSW, particularly along the Hume Highway corridor.
- QLD: Brisbane's fuel prices tend to be slightly lower than Sydney or Melbourne. Far North Queensland and outback areas can see prices 30-50 cents higher due to transport costs.
- WA: Perth enjoys some of Australia's cheapest metropolitan fuel prices thanks to proximity to refineries. However, remote Pilbara and Kimberley regions often pay $2.50+ per litre.
- SA: Adelaide prices sit between Sydney and Perth. The Eyre Peninsula and outback SA face significant price premiums.
- TAS: Island logistics mean Tasmanian prices are usually 5-15 cents above mainland capitals, with little variation across the state.
- ACT: Canberra prices mirror NSW, with regular cross-border shopping to Queanbeyan when price cycles align.
- NT: Darwin has reasonable prices, but remote communities can pay $3+ per litre.
Common mistakes people make
- Using the manufacturer's claimed fuel consumption: Car makers list consumption figures under ideal test conditions. Real-world driving, especially with city traffic, air conditioning, and highway speeds above 100 km/h, typically adds 15-30% to these numbers. Check your own fuel economy over several tanks to get accurate trip costs.
- Forgetting to account for load and terrain: A loaded car with roof racks climbing the Blue Mountains or towing a trailer will burn significantly more fuel than the flat, empty baseline. Add at least 20% to your consumption estimate if you're carrying camping gear or bikes, more if towing.
- Comparing fuel cost only when considering driving versus flying: Many people calculate just the petrol cost and think driving is cheaper. They forget vehicle depreciation (roughly 15 cents per km), tyres, servicing, insurance, and tolls. The ATO's 88 cents per km rate for 2024-25 reflects the true cost. For a 1,000 km trip, that's $880 total cost, not just the $120 in fuel.
- Not checking fuel prices before a long trip: Petrol can vary by 40 cents per litre within the same city depending on where you are in the price cycle. Apps like Petrol Spy or ACCC's Fuel Price Finder can save you $20-30 on a long-distance tank.
What this calculator doesn't account for
This calculator gives you the direct fuel cost only. It doesn't account for vehicle depreciation, which is typically your biggest driving cost at 10-20 cents per kilometre depending on your car's value. It also doesn't include tolls (Sydney to Newcastle can add $15 each way), parking fees, or wear items like tyres and brakes.
The calculator assumes steady highway driving. It can't factor in city traffic, where stop-start conditions can increase fuel use by 30-40%, or mountainous terrain. It also doesn't consider seasonal factors like winter fuel blends or running the air conditioner in summer, both of which affect consumption.
If you're claiming work-related car expenses with the ATO, the 88 cents per kilometre method (for the 2024-25 financial year) is simpler and usually more generous than calculating actual costs for trips under 5,000 km per year.
Edge cases and nuances
Claiming fuel as a business expense: If you're self-employed or a sole trader, you can claim actual fuel costs, but only for the business portion of your trip. The ATO requires a logbook kept for 12 continuous weeks showing business versus private use. If your logbook shows 70% business use, you can claim 70% of your fuel. Alternatively, the cents per kilometre method (88 cents for 2024-25, up to 5,000 km) covers all car expenses and requires no receipts, just a reasonable calculation of work kilometres.
Salary packaging and novated leases: If your fuel is part of a novated lease arrangement, the cost is deducted from your pre-tax salary, effectively giving you a discount equal to your marginal tax rate plus Medicare levy. Someone on the 32.5% tax bracket saves about 34.5 cents for every dollar of fuel, changing the real cost equation significantly.
Hybrid and plug-in hybrid vehicles: These cars have two fuel consumption figures, electric-only and petrol. Real-world costs depend entirely on your charging habits. A plug-in hybrid charged daily might use 2 litres per 100 km, but never charged it might use 7 litres per 100 km, worse than a regular petrol car due to carrying a heavy battery.
