How do I calculate fuel cost for a road trip?

Fuel cost = (Distance ÷ Fuel Efficiency) × Fuel Price. For MPG: divide miles by MPG to get gallons needed, then multiply by price per gallon. For L/100km: divide km by 100 to get hundreds of km, then multiply by L/100km and price per liter.

How do I convert MPG to L/100km?

L/100km = 235.214 ÷ MPG. For example, 30 MPG = 235.214 ÷ 30 = 7.84 L/100km. To go the other way: MPG = 235.214 ÷ L/100km.

How much does a 300-mile road trip cost in gas?

At 30 MPG and $3.50/gallon: 300 miles ÷ 30 MPG = 10 gallons × $3.50 = $35.00 total. At 25 MPG: $42.00. The exact answer depends on your vehicle's fuel efficiency and local gas prices.

Is an electric vehicle cheaper to run than a gas car?

In most cases yes. A typical EV uses about 3–4 miles per kWh (≈25–33 kWh/100mi). At $0.16/kWh, a 300-mile trip costs about $12–16 in electricity vs $35–45 in gas at typical prices. Use the EV Comparison mode to compare for your specific trip.

How does the passenger split feature work?

Enter the number of passengers (including the driver). The tool divides the total fuel cost equally. For example, a $60 trip shared by 4 people costs $15 each. You can also use the 'driver pays full' option where only passengers split the cost.

Fuel Cost Calculator — Gas Cost for Any Trip

Calculate Trip Cost

Trip Distance

Fuel Efficiency

Fuel Price

Enter your local price for accurate results

Round trip (×2 distance)

$35.00

Total fuel cost · 300 miles at 30 MPG

👥 Passenger Split

Number of people (incl. driver)

Driver pays full — only passengers split

⚡ EV Comparison

EV Efficiency

Tesla Model 3 avg ≈ 3.5 mi/kWh

Electricity Price

/kWh

US avg ≈ $0.16/kWh (2024)

📍 Multi-Stop Route

📅 Monthly Commute Cost

Days per week

Weeks per month

Uses the distance field above as one-way commute distance.

How to Calculate Trip Fuel Cost

The Formula (US — Miles & MPG)

Gallons needed = Distance (miles) ÷ MPG
Total cost = Gallons × Price per gallon

Example: 450 miles at 28 MPG with gas at $3.85/gallon:
450 ÷ 28 = 16.07 gallons × $3.85 = $61.87 total.

The Formula (Metric — km & L/100km)

Liters needed = (Distance (km) ÷ 100) × L/100km
Total cost = Liters × Price per liter

Example: 700 km at 8 L/100km with fuel at €1.70/L:
(700 ÷ 100) × 8 = 56 liters × €1.70 = €95.20 total.

Unit Conversions

MPG → L/100km: L/100km = 235.214 ÷ MPG (e.g., 30 MPG = 7.84 L/100km)
L/100km → km/L: km/L = 100 ÷ L/100km
miles → km: multiply by 1.60934
$/gallon → $/liter: divide by 3.78541

Gas vs Electric: Cost Per Mile Compared

At current typical US prices (gas ~$3.50/gal, electricity ~$0.16/kWh), a 30-MPG car costs about $0.12 per mile in fuel. A typical EV at 3.5 mi/kWh costs about $0.046 per mile — roughly 3× cheaper to run.

The savings are larger if you charge at home (often $0.10–0.13/kWh off-peak) and less dramatic if you rely on public DC fast chargers ($0.35–0.60/kWh). The EV comparison mode above lets you enter your actual electricity rate for an accurate comparison.

Other Factors to Consider

Fuel efficiency drops at highway speeds above 55–60 mph (typically 10–15% below EPA ratings). In urban stop-start driving, efficiency may be higher for hybrids and EVs, lower for gas cars.
AC and heating increase fuel consumption by 5–25%.
Payload and towing can reduce MPG by 20–50%.
Tire pressure: under-inflated tires reduce MPG by up to 3% per PSI below optimal.

Tips to Reduce Fuel Costs on Road Trips

Maintain 55–65 mph. Fuel economy drops sharply above 65 mph — at 75 mph you're using roughly 25% more fuel than at 55 mph.
Use cruise control on flat highways. Consistent speed is far more efficient than accelerating and decelerating.
Check tire pressure before you leave. Each PSI underinflated costs about 0.2% in fuel economy; tires lose 1 PSI per month naturally.
Reduce roof cargo when possible. Roof boxes and bike racks increase drag significantly — a full roof box can cut highway MPG by 10–25%.
Carpool. The passenger split calculator shows exactly how much each person saves. A 4-person carpool quarters your fuel cost.
Fill up away from highway rest stops. Gas stations at exits and in cities tend to be significantly cheaper than highway service stations.

⛽ Fuel Cost Calculator