Fuel Cost Calculator
Fuel is the largest running cost of driving, and the only one you can estimate precisely before a trip. This fuel cost calculator combines distance, your car’s consumption and the current fuel price to show what any journey will cost — in litres and dollars, or gallons and dollars.
Switch between metric (km, L/100km) and imperial (miles, MPG) with the toggle — the calculator handles both conventions.
Enter valid values to see the results.
Formula
L/100km and MPG measure the same thing in opposite directions: with L/100km lower is better, with MPG higher is better. 8 L/100km ≈ 29.4 MPG; 6 L/100km ≈ 39.2 MPG.
How to measure
- Distance: use your map app’s route distance, and include detours — city driving adds 10–20% to consumption.
- Consumption: find your real figure with the Fuel Economy Calculator from a fill-up, not the brochure number.
- Fuel price: the price per litre or per gallon at the stations you will actually use along the route.
Worked example
Practical tips
- Real-world consumption is typically 15–25% above the official figure — measure yours over several fill-ups.
- Highway cruising at 90–100 km/h uses noticeably less fuel than 130 km/h: aerodynamic drag grows with the square of speed.
- A roof box can add 10–25% to consumption on the highway — remove it when not needed.
- Under-inflated tires add ~3% to fuel use for every 0.3 bar (4 psi) below spec.
Fuel cost of a 500 km (310 mi) trip at $1.50/L ($5.68/gal)
| Consumption | Fuel used | Cost |
|---|---|---|
| 5 L/100km (47 MPG) | 25 L | $37.50 |
| 7.5 L/100km (31 MPG) | 37.5 L | $56.25 |
| 10 L/100km (23.5 MPG) | 50 L | $75.00 |
| 13 L/100km (18 MPG) | 65 L | $97.50 |
Common mistakes
- 1 Using the brochure consumption figure instead of the measured real-world one.
- 2 Mixing up L/100km and MPG when switching units — they move in opposite directions.
- 3 Forgetting the return leg: a “weekend trip” cost is usually double the one-way estimate.
Frequently asked questions
How do I calculate fuel cost for a trip?
Multiply the distance by your consumption per unit of distance, then by the fuel price. For metric: km × (L/100km ÷ 100) × price per litre. This calculator does it in one step.
What is a good fuel consumption figure?
Modern compact cars achieve 5–6.5 L/100km (36–47 MPG); SUVs and trucks 9–13 L/100km (18–26 MPG). Hybrids can go below 4.5 L/100km (52+ MPG).
Does air conditioning increase fuel cost?
Yes, by roughly 5–10% in city driving. On the highway, open windows create more drag than the AC compressor uses.
How much does driving style change fuel cost?
Aggressive acceleration and braking can raise consumption by 20–30% in urban driving — on a 15,000 km year that is easily $300–500.