Fuel Cost Calculator

About the Fuel Cost Calculator

The fuel cost calculator computes the exact cost of petrol, diesel, LPG, or E10 for any road trip — whether it is a single destination drive or a multi-leg journey with several stops — using your vehicle's fuel efficiency in the unit system most familiar to you. Australian and New Zealand drivers typically express fuel efficiency in litres per 100 kilometres (L/100km), where a lower number means a more economical vehicle. The average Australian passenger car consumes 9–12 L/100km, while fuel-efficient small cars reach 5–7 L/100km and larger SUVs and utes often consume 12–18 L/100km. American drivers use miles per gallon (MPG), where a higher number indicates better fuel economy — the average US passenger car achieves around 28 MPG on the combined cycle. Asian and some European markets use kilometres per litre (km/L), the inverse of L/100km. Our calculator supports all three conventions and converts between them automatically. Fuel price is the other key variable, and it changes constantly. Australian petrol prices in capital cities typically range from $1.60 to $2.20 per litre depending on the day of the weekly price cycle, with Tuesday through Thursday historically offering the cheapest fuel in major cities. In the US, petrol (gas) prices vary enormously by state and season, typically ranging from $3.00 to $5.00 per gallon. The calculator also estimates the CO₂ emissions for your journey, calculated from the fuel used and the CO₂ emission factor of your selected fuel type — petrol produces approximately 2.31 kg of CO₂ per litre burned, diesel produces 2.68 kg, LPG produces 1.51 kg, and E10 (10% ethanol blend) produces approximately 2.24 kg. The multi-stop road trip feature is particularly useful for planning holidays or interstate drives: you can add each leg of the journey separately, see the cost and fuel consumption per segment, and get a total for the entire route. For example, a Sydney to Melbourne direct drive (878 km) costs approximately $142 in petrol at 9 L/100km and $1.80/L, while adding a detour through Canberra (Sydney → Canberra 285km, Canberra → Melbourne 660km) adds about $13 in extra fuel cost for the 67km detour.

How It Works

Fuel Used = (Distance km / 100) × L/100km. For MPG: L/100km = 235.215 / MPG first, then apply formula. Total Cost = Fuel Used × Price per Litre. CO₂ = Fuel Used × CO₂ factor per litre (petrol: 2.31, diesel: 2.68, LPG: 1.51, E10: 2.24). Cost per km = Total Cost / Distance. Example: Sydney to Melbourne, 878 km, 9 L/100km, $1.85/L petrol. Fuel = (878/100) × 9 = 79.0 L. Cost = 79.0 × $1.85 = $146.15. CO₂ = 79.0 × 2.31 = 182.5 kg.

Tips & Best Practices

• ✓Australian petrol prices follow a weekly cycle in most capital cities: prices typically peak on Thursday or Friday and are cheapest on Monday or Tuesday. The ACCC publishes average city prices daily — check before a long trip to time your fill-up.
• ✓Driving at 100 km/h instead of 110 km/h reduces fuel consumption by approximately 10-15% due to aerodynamic drag increasing with the square of speed. On a 1,000 km trip at 9 L/100km, reducing speed saves roughly 10-15 litres and adds only 6 minutes of travel time.
• ✓Tyre pressure affects fuel consumption by 0.5-1% per PSI below the recommended pressure. Check tyres before any long trip — underinflated tyres are the most commonly neglected source of increased fuel consumption.
• ✓Air conditioning increases fuel consumption by approximately 5-15% depending on conditions. At low speeds in traffic, AC uses more fuel proportionally. At highway speeds, closing windows and using AC is more efficient than the aerodynamic drag of open windows above about 80 km/h.
• ✓LPG (autogas) typically costs 60-70% of petrol per litre but has approximately 25% lower energy density — meaning you use more volume for the same distance. Net savings are approximately 30-40% per km compared to petrol.
• ✓The Australian Government's Green Vehicle Guide (greenvehicleguide.gov.au) publishes official combined cycle fuel consumption figures for all vehicles sold in Australia. Use these for accurate planning rather than manufacturer claimed figures, which often reflect optimal lab conditions.
• ✓In the US, the EPA's fueleconomy.gov database provides real-world MPG estimates from actual driver submissions, which are typically 10-20% lower than the official combined EPA rating — use the 'real world' figures for accurate trip budgeting.
• ✓Electric vehicles have an equivalent fuel cost of approximately $2.50-4.50 per 100 km at typical Australian home electricity tariffs ($0.25-0.35/kWh), versus $15-20 per 100 km for an average petrol car — a saving of $10-15 per 100 km.

Who Uses This Calculator

Road trippers planning a holiday budget across multiple stops calculate the total fuel cost for the entire route before deciding whether to drive or fly. Daily commuters calculating their monthly fuel cost to compare against public transport costs. Employers calculating vehicle reimbursement amounts for staff who use personal vehicles for work travel. Fleet managers estimating fuel budgets for delivery or service routes. Electric vehicle owners comparing their electricity cost per km against equivalent petrol vehicle costs to quantify EV savings. Families with multiple vehicles choosing which car to take on a long trip based on fuel efficiency and cost.