How to Calculate Fuel Cost for Any Trip
Complete guide — fuel cost formulas, price tables, MPG conversion, CO2 emissions, and a free calculator
1. The Fuel Cost Formula
Calculating fuel cost requires three pieces of information:
- Trip distance in miles or kilometers
- Vehicle fuel efficiency in MPG (miles per gallon) or L/100km
- Fuel price per gallon or per liter
Using L/100km: Fuel cost = (Distance ÷ 100) × L/100km × Price per liter
Example (US): A 300-mile trip, car gets 30 MPG, gas at $3.50/gallon:
- Gallons needed: 300 ÷ 30 = 10 gallons
- Total cost: 10 × $3.50 = $35.00
- Cost per mile: $35 ÷ 300 = $0.117/mile
2. MPG vs L/100km: How to Convert
The US uses miles per gallon (higher = better). Europe uses liters per 100 km (lower = better). Here’s the conversion:
- MPG to L/100km: 235.215 ÷ MPG = L/100km
- L/100km to MPG: 235.215 ÷ L/100km = MPG
| MPG (US) | L/100km | Typical vehicle |
|---|---|---|
| 20 | 11.8 | Large SUV, truck |
| 25 | 9.4 | Mid-size SUV |
| 30 | 7.8 | Average sedan |
| 40 | 5.9 | Compact car |
| 50+ | 4.7 | Hybrid |
3. Average Fuel Prices by Country (2026)
| Country | Gas/Petrol | Diesel |
|---|---|---|
| United States | $3.30–3.80/gal | $3.60–4.20/gal |
| United Kingdom | £1.35–1.50/L | £1.40–1.55/L |
| Germany | €1.75–1.90/L | €1.60–1.75/L |
| France | €1.80–1.95/L | €1.65–1.80/L |
| Italy | €1.78–1.86/L | €1.65–1.75/L |
4. Real Trip Cost Examples
Here are fuel cost estimates for popular US road trips (sedan, 30 MPG, $3.50/gal):
| Route | Distance | Gallons | Cost |
|---|---|---|---|
| New York → Boston | 215 mi | 7.2 | $25.08 |
| LA → San Francisco | 380 mi | 12.7 | $44.33 |
| Chicago → Miami | 1,380 mi | 46.0 | $161.00 |
| Dallas → Denver | 790 mi | 26.3 | $92.17 |
5. Gas vs Diesel vs Electric: Annual Cost
Comparison for 12,000 miles/year (US average):
| Fuel type | Efficiency | Annual cost | CO2/year |
|---|---|---|---|
| Gasoline | 30 MPG | $1,400 | 3,555 kg |
| Diesel | 35 MPG | $1,337 | 3,455 kg |
| Hybrid | 50 MPG | $840 | 2,133 kg |
| Electric | 3.5 mi/kWh | $514 | 0 (direct) |
6. CO2 Emissions by Fuel Type
Each gallon/liter of fuel burned produces a specific amount of CO2:
- Gasoline: 8.89 kg CO2 per gallon (2.31 kg/liter)
- Diesel: 10.18 kg CO2 per gallon (2.68 kg/liter)
- LPG: 5.68 kg CO2 per gallon (1.51 kg/liter)
- Electric: 0 kg direct (grid emissions vary by region)
A single tree absorbs about 22 kg (48 lbs) of CO2 per year. Our fuel calculator automatically shows emissions and the number of trees needed to offset each trip.
7. Tips to Reduce Fuel Costs
- Maintain steady speed: use cruise control on highways. Aggressive driving wastes up to 33% more fuel.
- Check tire pressure: under-inflated tires increase fuel consumption by up to 3%.
- Reduce idling: turn off the engine if stopped for more than 60 seconds.
- Remove excess weight: every 100 lbs (45 kg) increases fuel consumption by 1–2%.
- Use AC wisely: air conditioning can increase fuel use by 10–15% in city driving.
- Compare gas prices: apps like GasBuddy show the cheapest stations near you.
- Carpool: split the cost with passengers. Our calculator supports cost splitting.
8. Free Fuel Cost Calculator
Our fuel cost calculator is the most complete free tool available:
- Supports gas, diesel, LPG, and electric vehicles
- Calculates total cost, cost per mile/km, fuel needed, and CO2 emissions
- Automatic comparison across all fuel types
- Cost splitting between passengers
- Pre-loaded prices for US, UK, Italy, Germany, and France
- Works on desktop and mobile, no registration needed
Need more tools? Try our savings calculator, VAT calculator, or browse all free ANIMA tools.