Fuel Cost Calculator
What a Trip Actually Costs at the Pump
Fuel economy numbers on a window sticker are only useful once you translate them into dollars for a specific trip. Distance, your vehicle's real-world efficiency, and the local price per gallon or liter combine into one figure that matters at budgeting time — and small differences in any of the three compound quickly over a round trip or a regular commute.
The Formula
Imperial: Fuel Used = Distance ÷ MPG
Cost = Fuel Used × Price per Gallon
Metric: Fuel Used = (Distance × L/100km) ÷ 100
Cost = Fuel Used × Price per Liter
Cost = Fuel Used × Price per Gallon
Metric: Fuel Used = (Distance × L/100km) ÷ 100
Cost = Fuel Used × Price per Liter
Round-trip mode simply doubles the one-way distance before either formula runs, so you don't have to do the multiplication by hand.
Where This Matters
- Commute budgeting — a daily round trip adds up differently depending on whether a car returns 20 MPG or 40 MPG at the same fuel price.
- Road trip planning — entering total mileage before departure gives a realistic fuel budget line separate from lodging and food.
- Comparing vehicles — running the same trip distance through two different MPG figures shows the actual dollar gap between candidates, not just the MPG gap.
- Fuel price sensitivity — re-running the same distance at a higher price per gallon shows how exposed a low-MPG vehicle is to price swings at the pump.
Cost per 100 Miles by Fuel Economy
| Fuel Economy | Gallons Used | Cost |
|---|---|---|
| 20 MPG | 5.00 | $17.50 |
| 25 MPG | 4.00 | $14.00 |
| 30 MPG | 3.33 | $11.67 |
| 35 MPG | 2.86 | $10.00 |
| 40 MPG | 2.50 | $8.75 |
| 50 MPG | 2.00 | $7.00 |
Figures assume a constant $3.50/gallon price; substitute your local price for an exact comparison.
How to Use This Calculator
- Choose Imperial (miles, MPG, gallons) or Metric (km, L/100km, liters) from the unit selector.
- Enter the trip distance, your vehicle's fuel economy, and the current price per gallon or liter.
- Select One-Way Trip or Round Trip.
- Select Calculate to see the total fuel cost along with the estimated fuel used.
Related Calculations
Check your actual fuel economy first with the Mileage Calculator, or convert between MPG and L/100km using the Fuel Economy Calculator.