How Fuel Cost Is Calculated
A trip fuel estimate combines total distance, vehicle fuel consumption, and fuel price. This calculator first converts the selected distance, mileage, volume, and price units to kilometres and litres. It then calculates fuel required before adding tolls, parking, and other entered travel costs.
Using km/L
Fuel Needed = Distance ÷ km per Litre
Using L/100 km
Fuel Needed = Distance × L/100 km ÷ 100
Total trip cost equals estimated fuel cost plus the entered extra expenses. Cost per passenger divides this complete total by everyone sharing the journey, while the vehicle comparison isolates fuel cost because tolls and parking usually remain the same.
km/L, L/100 km, and MPG Explained
Kilometres per litre (km/L)
Distance travelled on one litre. Higher is more efficient.
Litres per 100 km (L/100 km)
Fuel consumed over 100 kilometres. Lower is more efficient.
US miles per gallon (US MPG)
Miles travelled using one US gallon, equal to about 3.785 litres.
Imperial MPG
Miles travelled using one Imperial gallon, equal to about 4.546 litres.
US MPG and Imperial MPG are not interchangeable. Selecting the correct gallon standard matters for both mileage and fuel-price conversions. The results panel displays all four measures together so specifications from different markets can be compared consistently.
Measuring Real-World Vehicle Mileage
For a practical estimate, record the distance driven and fuel used between consistent fill-ups. The quick mileage section converts the result to every supported unit and can apply it directly to the trip-cost calculation.
- Fill the tank using a consistent method and reset the trip meter
- Drive normally across a representative mix of roads and traffic
- Refill and record both distance travelled and fuel added
- Repeat across several tanks to reduce one-off measurement variation
- Check tyre pressure, maintenance, load, and excessive idling
- Use the measured figure rather than relying only on advertised economy
Planning a More Realistic Road-Trip Budget
Route distance alone does not capture every driving expense. Include expected tolls, parking, ferries, access fees, and other route-specific costs. Add extra margin when traffic, mountain roads, weather, detours, roof racks, towing, or a heavily loaded vehicle may reduce fuel economy.
Fuel prices and mileage can change during a journey
A single price and mileage value is a planning average. For long routes, consider the likely price range and calculate a conservative scenario with slightly higher consumption or fuel price.
Important: Results Are Estimates
Actual fuel use and cost depend on the route, traffic, speed, driving style, weather, vehicle condition, load, pump measurement, and changing prices. The optional CO₂ result estimates tailpipe fuel combustion only and should not be treated as a certified emissions or lifecycle assessment.