Fuel Cost Calculator
Trip fuel cost based on MPG, distance, and gas price. Supports US (MPG) and metric (L/100km). Compare vehicles or estimate annual fuel spend.
About the Fuel Cost Calculator
The Fuel Cost Calculator estimates the gas cost for any road trip based on distance, your vehicle's fuel economy, and current gas price. Supports both US units (MPG, $/gallon) and metric (L/100km, €/liter). The tool also handles round-trip vs one-way, multiple drivers splitting the cost, and side-by-side comparisons between two vehicles.
Beyond single trips, the calculator projects annual fuel spend based on your typical miles driven and average fuel price, plus models the savings of switching to a more efficient vehicle. The EV mode replaces MPG with kWh/mi and electricity rate per kWh, so you can directly compare what a trip costs in gas vs in electricity for the same route.
Common use cases
- Estimate gas cost before a road trip
- Compare fuel cost of two cars before purchasing
- Calculate fuel reimbursement for business mileage
- Compare ICE vs EV operating cost for the same trip
Tips for accurate results
Real-world MPG runs 10-20% below EPA-rated MPG on most vehicles due to acceleration patterns, AC use, traffic, and weather. The calculator includes a "realistic" toggle that applies a 0.85x multiplier to your EPA number - useful when budgeting actual fuel spend for a long drive. For comparison shopping between two cars, stick with EPA numbers since both are inflated by similar amounts.
Privacy & data handling
The Fuel Cost Calculator runs entirely in your browser. Nothing you enter is uploaded, logged, or shared with third parties - the math happens locally and your inputs disappear when you close the tab. There is no signup, no email collection, and no daily-use limit.
How is fuel cost calculated?
For US: distance ÷ MPG = gallons needed; gallons × $/gallon = total cost. For metric: distance × (L/100km ÷ 100) = liters needed; liters × €/liter = total cost. The tool handles both unit systems and converts between them as needed.
How accurate is the MPG estimate?
EPA-rated MPG is measured on a controlled cycle; real-world driving is typically 10-20% worse due to acceleration, weather, A/C, and traffic. The tool defaults to EPA combined MPG with an option to apply a "realistic" 0.85x multiplier - useful when budgeting for a long drive vs comparing two cars.
Can I compare two vehicles?
Yes - side-by-side comparison mode lets you enter both vehicles' MPG and shows the cost difference for a given trip distance, plus annual cost difference at your typical miles driven. Useful when shopping for a more efficient car: "I drive 12,000 miles/year, switching from 25 MPG to 35 MPG saves $X."
What about hybrid and EV cost comparisons?
For hybrids, use the combined EPA MPG. For EVs, switch to "electric" mode and enter kWh/100mi (or kWh/100km) and electricity rate per kWh. The tool will compute electricity cost for the trip and let you compare against the gas version of the same trip.
How can I lower fuel cost on a long trip?
Three biggest levers: drive 5-10 mph slower (highway MPG drops sharply above 65 mph), inflate tires properly (under-inflation costs 2-4% MPG), and remove roof racks/cargo when not needed (3-10% MPG penalty at highway speed). On a 1,000-mile trip these can save 5-8 gallons of gas combined.
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