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Fuel Cost Calculator — Trip Cost & Gas Price Calculator

Calculate fuel costs for your trips and optimize your travel budget

miles
MPG
$per gallon

Fuel Cost Calculator: Trip Cost and Gas Price Calculator

Table of Contents - Fuel Cost

How to Use This Calculator - Fuel Cost

Select your Unit System: Imperial (miles, MPG, gallons) or Metric (kilometers, km/L, liters).

Enter the Distance of your trip. Use mapping tools like Google Maps for accurate distances.

Enter your vehicle's Fuel Efficiency. Find this in your owner's manual, on a fuel economy sticker, or from your trip computer's actual consumption.

Enter the Current Fuel Price per gallon or liter.

Select Trip Type: One-way or Round-trip (doubles the distance automatically).

Click "Calculate" to see results. The output displays:

  • Total distance traveled
  • Fuel needed in gallons/liters
  • Total cost
  • Cost per mile/kilometer
  • Alternative unit conversions (e.g., equivalent in liters if you entered gallons)

The Core Principle: Distance, Efficiency, and Price

Fuel cost follows a simple formula: Fuel Cost = (Distance ÷ Fuel Efficiency) × Fuel Price

Fuel Efficiency (MPG or km/L) tells you how far you travel per unit of fuel. Higher efficiency means lower cost per mile.

Distance is the actual road distance, not straight-line distance. Mountain routes and city traffic add distance and reduce efficiency.

Fuel Price varies by location, grade, and time. Premium fuel costs more but may not improve efficiency in vehicles designed for regular.

Real-world efficiency often differs from EPA ratings by 10-20%. Factors include driving style, terrain, weather, and vehicle condition.

How to Calculate Fuel Costs Manually

Basic calculation (Imperial): Fuel needed = Distance ÷ MPG Cost = Fuel needed × Price per gallon

Example: 350 miles, 28 MPG, $3.50/gallon Fuel = 350 ÷ 28 = 12.5 gallons Cost = 12.5 × $3.50 = $43.75

Round trip: Double the distance before calculating. 350 miles × 2 = 700 miles Fuel = 700 ÷ 28 = 25 gallons Cost = 25 × $3.50 = $87.50

Metric calculation: Fuel needed (L) = Distance (km) ÷ Efficiency (km/L)

Example: 500 km, 12 km/L, €1.60/L Fuel = 500 ÷ 12 = 41.7 liters Cost = 41.7 × €1.60 = €66.67

Converting L/100km to km/L: km/L = 100 ÷ L/100km

Example: 8 L/100km = 100 ÷ 8 = 12.5 km/L

Converting MPG to L/100km: L/100km = 235.215 ÷ MPG

Example: 30 MPG = 235.215 ÷ 30 = 7.84 L/100km

Real-World Applications

Vacation budgeting. A 2,000-mile road trip at 25 MPG with $3.50 gas costs $280 in fuel. Add that to hotel and food budgets.

Commute cost calculation. A 30-mile daily commute (60 miles round trip) at 32 MPG, $3.50/gallon, 22 workdays/month: 60 × 22 = 1,320 miles. Fuel = 41.25 gallons. Cost = $144/month.

Vehicle comparison. An SUV getting 22 MPG versus a sedan getting 35 MPG, both driving 12,000 miles/year at $3.50/gallon: SUV costs $1,909/year; sedan costs $1,200. Difference: $709/year.

Rideshare break-even. Uber/Lyft charges $25 for your regular trip. Your car: 40 miles × $3.50 ÷ 28 MPG = $5 in fuel. But add insurance, depreciation, and parking—maybe rideshare is competitive.

Route optimization. The scenic route is 50 miles longer. At 25 MPG and $3.50/gallon, that's $7 extra. Is the scenery worth $7?

Scenarios People Actually Run Into

The EPA versus reality gap. Your car is rated 30 MPG but you're getting 24 MPG. City driving, aggressive acceleration, underinflated tires, and roof racks all reduce efficiency. Use your actual consumption for accurate cost estimates.

The highway versus city surprise. Highway driving at 65 MPH gives you 32 MPG. At 80 MPH, you get 26 MPG. The faster trip uses 23% more fuel—time savings have a cost.

The fuel grade question. Your manual says "regular unleaded." Premium costs $0.50 more per gallon. Over 12,000 miles at 25 MPG (480 gallons), that's $240/year wasted on unnecessary premium.

The mountain route reality. The mountain pass adds 20 miles but cuts an hour of traffic. However, climbing reduces efficiency significantly—your 28 MPG drops to 20 MPG uphill. Factor both distance and efficiency changes.

The winter efficiency drop. Cold weather reduces fuel efficiency by 10-20%. Your 30 MPG summer car gets 25 MPG in winter. Budget accordingly for cold-weather trips.

Trade-Offs and Decisions People Underestimate

Time versus fuel cost. The toll road is 20 miles shorter but costs $15. At 25 MPG and $3.50/gallon, the 20-mile detour costs $2.80 in fuel. The toll saves $2.80 in fuel but costs $15. Unless you highly value time, skip the toll.

Speed versus efficiency. Aerodynamic drag increases with the square of speed. Dropping from 75 to 65 MPH can improve efficiency 10-15%, saving significant fuel on long trips.

Vehicle choice for trip. Your spouse's sedan gets 35 MPG; your SUV gets 22 MPG. For a 600-mile trip: sedan costs $60; SUV costs $95. Taking the sedan saves $35—enough for a nice dinner.

Fuel price timing. Prices fluctuate daily. Filling up before a holiday weekend when prices spike, or buying in lower-cost areas during your trip, can save $5-10 on a single tank.

Hybrid/EV for long trips. Your hybrid excels in city driving. On long highway trips, efficiency advantages diminish. A 50 MPG hybrid versus a 40 MPG gas car: 500 miles costs $35 versus $44—meaningful but not dramatic.

Common Mistakes and How to Recover

Using rated MPG instead of actual. EPA ratings are optimistic. Track your actual fuel consumption over several tanks for realistic cost estimates.

Forgetting round trip. If you're driving somewhere and back, double the distance. It's obvious but commonly overlooked.

Ignoring terrain effects. Mountain driving can cut efficiency 30-40%. Desert heat and headwinds also impact consumption.

Assuming constant prices. Fuel prices vary by state/country, urban/rural, and brand. A 500-mile trip might span $0.50/gallon price differences.

Not accounting for cargo. Roof boxes reduce aerodynamics. Extra weight (passengers, luggage) increases consumption. A loaded vehicle may get 10-15% worse efficiency than empty.

Related Topics

Carbon footprint. Each gallon of gas produces about 20 lbs of CO2. Your 500-mile trip at 25 MPG (20 gallons) produces 400 lbs of CO2.

Total cost of ownership. Fuel is just one component. Add insurance, depreciation, maintenance, and registration for true vehicle costs per mile.

Hypermiling. Techniques to maximize fuel efficiency: gentle acceleration, coasting, maintaining tire pressure, removing weight. Extreme hypermilers exceed EPA ratings.

Fuel economy standards. CAFE (Corporate Average Fuel Economy) standards require automakers to meet fleet-wide efficiency targets, pushing vehicle efficiency higher.

Alternative fuels. Electric, hybrid, hydrogen, biodiesel—each has different cost structures and availability considerations.

How This Calculator Works

Fuel needed calculation:

Imperial:

fuelNeeded = distance / mpg

Metric:

fuelNeeded = distance / kmPerL

Total cost:

totalCost = fuelNeeded × fuelPrice

Round trip adjustment:

totalDistance = (tripType === 'round-trip') ? distance × 2 : distance

Cost per mile/km:

costPerUnit = totalCost / totalDistance

Unit conversions:

milesToKm = miles × 1.60934
kmToMiles = km × 0.621371
gallonsToLiters = gallons × 3.78541
litersToGallons = liters × 0.264172
mpgToKmL = mpg × 0.425144
kmLToMpg = kmL × 2.35214

All calculations happen locally in your browser.

FAQs

Why is my actual MPG lower than the window sticker?

EPA testing uses ideal conditions. Real-world factors—traffic, terrain, climate, driving style—typically reduce efficiency by 10-20%.

How do I find my real fuel efficiency?

Fill tank completely. Reset trip odometer. Drive normally until nearly empty. Fill again, note gallons. Divide miles driven by gallons used.

Does premium fuel improve efficiency?

Only if your engine requires it. Vehicles designed for regular gain no benefit from premium—you're just paying more per gallon.

How much does speed affect fuel cost?

Roughly 1-2% efficiency loss per MPH above 50. Driving 80 versus 60 might cost 25-30% more fuel.

Should I calculate with current prices or average prices?

Current prices for immediate trips. Average or projected prices for budgeting ongoing costs like monthly commuting.

How does AC affect fuel economy?

AC typically reduces efficiency by 5-10%. At highway speeds, AC is more efficient than open windows (which create drag). At low speeds, windows down is more efficient.

Is it worth driving farther for cheaper gas?

Calculate the extra fuel cost of the detour. If saving $0.10/gallon requires 10 extra miles (costing $1.40 in fuel for a 15-gallon fill), and you only save $1.50, barely worth it.

How do I factor in tolls versus fuel savings?

Calculate fuel cost for both routes. Add toll costs. Compare totals. Often, the toll road saves time but costs more in total—worthwhile only if your time has high value.

What's the true cost per mile of driving?

Fuel is just one component. The IRS standard mileage rate (~$0.67/mile in 2024) includes depreciation, insurance, maintenance, and fuel. Use this for reimbursement calculations.

How do I optimize a multi-stop trip?

Plan the most efficient route order. Refuel where prices are lowest along the way. Combine errands to reduce total distance. Navigation apps often optimize stop order automatically.

Does premium fuel improve efficiency in regular cars?

No. If your car is designed for regular, premium provides no benefit—you're just paying more per gallon for the same miles. Only use premium if required by your owner's manual.

How do I account for varying fuel prices on a long trip?

Research prices along your route using apps like GasBuddy. Fill up in lower-cost areas, and avoid highway rest stops where prices are typically highest. The savings can be substantial on long trips.

What's the most accurate way to track my actual fuel efficiency?

Use the "fill to fill" method: fill tank completely, reset trip odometer, drive normally, refill completely, and divide miles by gallons. Repeat over several tanks for an accurate average.

How does driving style affect fuel cost?

Aggressive driving (rapid acceleration, hard braking) can reduce efficiency by 15-30%. Smooth, steady driving conserves momentum and fuel. Cruise control on highways helps maintain consistent, efficient speeds.

Should I factor in vehicle maintenance costs?

For trip-specific calculations, fuel cost is usually sufficient. For total cost of ownership or comparing vehicle options, include maintenance (oil changes, tires, repairs) and depreciation alongside fuel.

How does vehicle age affect fuel economy?

Older vehicles may lose 1-2% efficiency annually due to wear on engine components, oxygen sensors, and fuel system. Regular maintenance (air filters, spark plugs, proper tire inflation) helps maintain original efficiency.

What's the break-even point for buying a more efficient car?

Calculate: (Price difference between cars) / (Annual fuel savings). If a car costs $5,000 more but saves $1,000/year in fuel, break-even is 5 years. Factor in resale value and other ownership costs for complete analysis.

How do hybrid vehicles affect fuel cost calculations?

Hybrids vary their fuel efficiency based on driving conditions. City driving often achieves better mileage than highway (opposite of conventional cars). Use your actual trip computer data rather than EPA ratings for accurate hybrid fuel cost estimates.