How Fuel Cost Calculation Works
The calculator converts all inputs to common base units (kilometers and liters), performs the calculation, then displays results in both liters and US gallons:
Distance (km) — if using miles, multiplied by 1.609 to convert to kilometers.
Fuel Efficiency → km/L — all efficiency units are converted to kilometers per liter:
- mpg (US) → km/L: multiply by 0.4251 (1 mile / 1 US gallon ≈ 1.609 km / 3.785 L)
- L/100km → km/L: divide 100 by the value
- L/mi → km/L: divide 1 by (value / 1.609)
Fuel Used (L) = Distance (km) ÷ Fuel Efficiency (km/L)
Fuel Used (US gal) = Fuel Used (L) ÷ 3.785
Total Cost = Fuel Used (L) × Fuel Price (per L)
If the price is entered per gallon, it is first divided by 3.785 to get the price per liter.
How to Use the Calculator
- Choose the distance unit — kilometers or miles.
- Enter the trip distance — results appear as you type.
- Check “Round trip” if travelling there and back — distance doubles automatically.
- Select your fuel efficiency unit — km/L, mpg (US), L/100km, or L/mi — and enter your vehicle’s value.
- Pick a currency and price unit — per liter or per gallon — then enter the current fuel price.
- See fuel used and total cost update instantly at the bottom.
Practical Examples
| Trip | Distance | Efficiency | Price | Round Trip | Fuel Used | Total Cost |
|---|---|---|---|---|---|---|
| City commute | 30 km | 12 km/L | $1.85/L | No | 2.5 L | $4.63 |
| Road trip | 250 mi | 30 mpg | $3.50/gal | Yes | 63.1 L (16.7 gal) | $58.33 |
| Daily drive | 15 km | 8 L/100km | €1.60/L | No | 1.2 L | €1.92 |
| Cross-country | 800 mi | 25 mpg | £1.45/L | No | 121.1 L (32.0 gal) | £175.64 |
Improving Fuel Efficiency
| Strategy | Typical Savings |
|---|---|
| Maintain steady speed (90–100 km/h highway) | 10–15% |
| Keep tires properly inflated | 3–5% |
| Remove excess weight and roof racks | 2–5% |
| Regular engine maintenance | 4–10% |
| Avoid aggressive acceleration and braking | 15–30% |