Fuel Cost Calculator
Estimate the cost of fuel for your upcoming road trip or daily commute.
🏆 Planning Your Road Trip Budget
Everything you need to know about using this calculator and the math behind it.
How it Works
Estimates the total cost of gas for a trip based on your vehicle's fuel efficiency, the distance to be traveled, and the current price of fuel.
The Formula
Total Cost = (Distance / Fuel Efficiency) × Fuel Price.
Pro Tip
Tire pressure and driving speed significantly affect fuel efficiency. Drive steadily to save money on long trips.
Frequently Asked Questions
How does speed affect fuel consumption? +
Aerodynamic drag increases with the square of speed — doubling your speed quadruples drag. At highway speeds, aerodynamics is the dominant factor. The US Department of Energy estimates every 5 mph above 50 mph reduces fuel economy by roughly 7–14%. At 75 mph vs. 65 mph, you might use 15% more fuel for the same trip. Combined with freeway driving habits like drafting behind trucks (reduces drag by ~25%), speed is the biggest controllable variable in fuel cost.
What is MPG vs. L/100km? +
MPG (miles per gallon) is used in the US and UK: higher is more efficient. L/100km (liters per 100 km) is the metric standard used in most of the world: lower is more efficient. Converting: MPG (US) = 235.21 ÷ L/100km. A car rated at 7 L/100km = 33.6 MPG. Unlike MPG, the L/100km scale is linear — going from 10 to 9 L/100km saves the same fuel per 100km as going from 9 to 8 L/100km.
How can I improve my car's fuel efficiency? +
Top strategies: keep tires properly inflated (gain 0.5–3% MPG), use cruise control on highways (reduces speed variation), accelerate and brake smoothly, remove excess weight from the car, keep the air filter clean, use the recommended engine oil grade, avoid excessive idling, and minimize AC use on city streets. Combined, these habits can improve fuel economy by 10–25% compared to aggressive driving.
Is it worth driving further to get cheaper gas? +
Usually not. Each additional mile to reach a cheaper station uses fuel. For a car getting 30 MPG and gas at $3.50/gal, driving 2 extra miles costs about $0.23 in fuel. If the cheap station saves $0.10/gal on a 15-gallon fill-up ($1.50 savings), you lose money. Savings only materialize for large fill-ups with significant price differences and very short detours. GasBuddy or Google Maps can help evaluate the break-even point.
How do electric vehicles change this calculation? +
EVs use kWh per mile instead of gallons. The equivalent cost: divide electricity cost per kWh by miles per kWh. At $0.14/kWh and 4 miles/kWh, cost is $0.035/mile — vs. $0.12/mile for a 30 MPG gas car at $3.50/gal. Over 15,000 miles, that's $525 vs. $1,750 in fuel. However, EVs have higher purchase prices, and long trips require planning around charging infrastructure. Total cost of ownership comparisons vary significantly by location and driving patterns.