How to Use the Fuel Cost Calculator

Enter distance — the trip distance in km or miles.
Enter fuel efficiency — your vehicle's fuel consumption. Find this in your owner's manual, on the dashboard display, or from previous fuel fill-up calculations.
Enter fuel price — the current price per litre or gallon at your local station.
Read fuel cost — total cost for the trip.
Compare vehicles — run the calculator for different fuel efficiency values to compare the real cost difference between vehicles over your typical driving patterns.

⛽ Calculate your real fuel efficiency: Fill tank completely. Record mileage. Drive normally. Fill tank again — note litres added and mileage driven. Real efficiency = Litres ÷ (km ÷ 100). Manufacturer figures are often 15–25% better than real-world consumption.

Understanding Fuel Costs and Efficiency

⛽ Fuel Efficiency Units

L/100km (Europe, most of world): lower = more efficient. 5L/100km is very efficient, 12L/100km is poor. MPG (US/UK): higher = more efficient. 50 MPG is very efficient, 20 MPG is poor. To convert: L/100km = 235 ÷ MPG (US).

📊 Real vs Advertised MPG

Manufacturer fuel economy figures are measured under controlled test conditions. Real-world consumption is typically 15–25% worse due to: highway speeds above test conditions, air conditioning use, cold engine starts, payload (passengers/cargo), terrain, and driving style.

🚗 Factors Affecting Consumption

Speed: fuel consumption increases dramatically above 90 km/h — at 120 km/h consumption is 20–30% higher than at 90 km/h. Air conditioning: adds 5–20% to consumption. Tyres: under-inflated tyres add 3% per 10 PSI below recommended pressure. Roof racks: empty roof rack adds 5%, loaded adds 15–40%.

💰 Annual Fuel Cost

Annual cost = (Annual km ÷ 100) × Fuel efficiency (L/100km) × Fuel price. At 15,000 km/year, 8L/100km, $1.50/litre: (15,000 ÷ 100) × 8 × 1.50 = $1,800/year. This calculation makes vehicle fuel efficiency differences tangible in dollar terms.

🔋 EV Cost Comparison

Electric vehicle equivalent: (km ÷ 100) × kWh per 100km × electricity price. A Tesla Model 3 using 15 kWh/100km at $0.15/kWh costs $0.0225/km versus a petrol car at 8L/100km at $1.50/litre costing $0.12/km. EVs cost approximately 80% less per kilometre to fuel.

🌍 Carbon Cost

Burning 1 litre of petrol produces approximately 2.31 kg of CO2. At 8L/100km for 15,000 km/year: 15,000 × 0.08 × 2.31 = 2,772 kg CO2 annually. Carbon offset costs approximately $15–50 per tonne — so roughly $42–140 per year to offset average car emissions.

Reducing Fuel Costs

Driving technique

Smooth acceleration and braking reduces fuel consumption by 15–30% compared to aggressive driving. Anticipate traffic flow — coast to red lights rather than accelerating then braking. Maintain steady speed on highways — cruise control reduces fuel consumption by 7–14% on flat roads. Combined, these technique changes can cut fuel bills by $200–$400 per year for average drivers.

Vehicle selection economics

When comparing vehicles, calculate the 5-year total fuel cost difference. A vehicle getting 30 MPG versus 20 MPG saves 33% on fuel. At $1,500/year fuel cost, that's $500/year or $2,500 over 5 years. This real-world cost difference often justifies paying more for a more efficient vehicle — use this calculator with your actual driving distance to make the comparison concrete.

Fuel price timing

Fuel prices follow weekly patterns in many markets — typically lowest on Tuesday and Wednesday, highest on weekends and holidays. Filling up mid-week can save 3–8 cents per litre versus weekend prices. Over a year of weekly fill-ups, this difference amounts to $50–$150 in savings for average drivers — genuine savings for minimal effort.

⛽ Fuel saving checklist: Tyre pressure correct (check monthly) ✓. Air filter clean (replace every 15,000–30,000 km) ✓. Remove roof rack when not in use ✓. Use recommended fuel grade (premium in non-premium engine wastes money) ✓. Service on schedule (dirty oil increases consumption 5–15%) ✓. These maintenance items together reduce fuel consumption by 10–20%.

Frequently Asked Questions

What is L/100km?

Litres per 100 kilometres (L/100km) is the fuel efficiency standard used in Europe, Australia, and most of Asia. Lower is better — a 6L/100km car is more fuel-efficient than a 10L/100km car. To convert to MPG (US): divide 235 by the L/100km figure.

How do I calculate fuel cost?

Fuel Cost = (Distance ÷ 100) × Fuel Efficiency (L/100km) × Price per litre. Example: 500km trip in a car doing 8L/100km at $1.80/L = (500÷100) × 8 × 1.80 = $72.

What affects fuel efficiency?

Speed (highway driving at 90–100km/h is most efficient), tyre pressure (underinflated tyres increase consumption 3%), air conditioning (adds 5–15%), load weight, driving style (aggressive acceleration wastes fuel), and vehicle maintenance (dirty air filters, old spark plugs).