Fuel Cost Calculator
Calculate the fuel cost for any road trip. Enter distance, fuel efficiency, and fuel price.
How to use this tool
- Enter distance, fuel efficiency and fuel price in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your trip cost and the full breakdown beneath it.
Calculate how much fuel your trip will use and how much it will cost.
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
Fuel used: F = distance × efficiency / 100 (litres)
Trip cost: cost = F × price
where distance is in km, efficiency in L/100 km, and price in $/L.
How it works
Fuel consumption is calculated by multiplying distance (km) by the vehicle's fuel efficiency (L/100 km) and dividing by 100 to convert the per-100 km rate to the actual litres used; the trip cost is then simply the fuel volume multiplied by the price per litre.
The result is accurate for constant fuel economy over flat terrain; real-world costs vary with driving style, gradient, load, traffic, and fuel type.
Worked example
Worked example — 100 km, 8 L/100 km, $1.80/L
- Fuel used = 100 km × 8 L/100 km / 100 = 8 L.
- Trip cost = 8 L × $1.80/L = $14.40.
Fuel used = 8.0 L; trip cost = $14.40.
Common mistakes to avoid
- Using the manufacturer combined fuel economy rating instead of real-world highway consumption — actual L/100 km on a highway trip is usually 10-20% higher than the official figure.
- Entering distance in miles but efficiency in L/100 km (or vice versa) — mixing units produces a nonsensical result.
- Forgetting that fuel prices vary along the route; using the home city price can underestimate cost on remote or motorway stretches.
Key terms
- Fuel efficiency (L/100 km)
- The volume of fuel consumed per 100 kilometres travelled; lower numbers indicate a more economical vehicle.
- Fuel cost
- The total monetary cost of fuel for a given trip, equal to litres consumed multiplied by the price per litre.
- Trip distance
- The total one-way or round-trip distance driven, typically in kilometres for metric fuel calculations.
- Fuel price ($/L)
- The retail price of fuel per litre at the pump; varies by region, fuel grade, and market conditions.
- Flat fuel economy assumption
- The simplification that a vehicle maintains exactly the stated L/100 km throughout the trip; actual consumption varies with speed, load, and terrain.
Frequently asked questions
- How do I calculate fuel cost for a trip?
- Divide the distance by 100, multiply by your car's L/100km figure to get litres used, then multiply by the fuel price per litre.