How It Works
The fuel cost calculator applies a simple ratio between distance and efficiency, then multiplies by fuel price:
Metric: Fuel (L) = (Distance / 100) x L/100km then Cost = Fuel x Price per litre
Imperial: Fuel (gal) = Distance / MPG then Cost = Fuel x Price per gallon
If the return trip option is enabled, the calculator doubles the distance before computing fuel and cost. The chart then splits the result into one-way and return segments so you can see each leg separately.
Variable Definitions
Trip Distance is the one-way length of your journey in kilometres or miles. You can find this from your car's trip odometer, a mapping app, or the route planner of your choice. A common mistake is entering the round-trip distance and also enabling the return trip toggle, which would double the actual distance. Always enter one-way distance and use the toggle if you need the round trip.
Fuel Efficiency describes how much fuel your vehicle uses. In metric, this is litres per 100 kilometres — lower is better (a Toyota Corolla does about 7 L/100km on the highway). In imperial, it is miles per gallon — higher is better (the same car gets about 34 MPG). Factory-listed efficiency is usually 10-20% better than real-world driving, so consider adding a buffer.
Fuel Price is the cost per litre or gallon at the pump. Prices vary by region, station, and fuel grade. Use the price you expect to pay on the trip, not the cheapest or most expensive you have seen. For long trips crossing regions, an average of prices along the route is a practical approach.
Return Trip is a simple toggle that doubles the distance. It saves you from doing the mental math of multiplying by two. When enabled, the chart shows two stacked bars — one-way and return — so you can clearly see how the cost doubles.
Edge Cases and Advanced Scenarios
City vs highway mix on a single trip: Most trips include both city and highway segments. If you drive 100 km on the highway at 7 L/100km and 50 km in the city at 10 L/100km, the combined efficiency is not simply the average. Calculate each segment separately — 7.0 L for highway + 5.0 L for city = 12.0 L total for 150 km, or an effective 8.0 L/100km. Enter this blended rate for the best estimate.
Elevation and terrain effects: Driving through mountainous terrain can increase fuel consumption by 15-30%. Steep climbs require more engine power, and while descents recover some energy, the net effect is always higher consumption. If your trip includes significant mountain passes, increase your efficiency value by 15-20% (e.g., from 8 to 9.5 L/100km) for a more realistic estimate.
What to Do with Your Result
Compare fuel cost to other transport. A round trip costing $120 in fuel might be cheaper than two plane tickets — or not, once you add tolls, parking, and vehicle wear. Use this number as one data point in a larger comparison.
Budget for the trip. Add 10-15% to the calculated fuel cost as a buffer for detours, traffic, and price variations along the route. This prevents mid-trip surprises at the pump.
Split costs fairly when carpooling. Share the fuel cost URL with passengers. Divide the total by the number of riders for an easy, transparent cost split.
Plan fuel stops. Divide your tank capacity by the litres-per-100km rate to find your range. On a 500 km trip with a 50 L tank and 8 L/100km efficiency, you can travel 625 km on a full tank — so you can make it without stopping. If your range is less than the trip distance, plan a refueling stop near the midpoint.