Fuel Cost Calculator

This fuel cost calculator works as a trip cost calculator, gas cost calculator, and driving cost calculator in one tool. Punch in three numbers and you get the gas cost for a road trip, the fuel cost per mile, plus projected monthly and annual fuel spend. It handles both US MPG and metric L/100km so it works for a Miami-to-Atlanta drive or a Paris-to-Berlin run.

1. Choose your unit system. US drivers typically use MPG (miles per gallon). Most other countries use L/100km (liters per 100 kilometers). Toggle the buttons at the top of the widget.
2. Enter your trip distance. Enter the one-way distance of the road trip you want to estimate. For a round-trip gas cost, double it, or use the round-trip note in the formula section below.
3. Enter your fuel efficiency (MPG). Find your vehicle's MPG rating on the window sticker, your owner's manual, or fueleconomy.gov. For a more accurate gas trip cost, track your own fuel usage over several fill-ups and average them.
4. Enter the current gas price per gallon. Check GasBuddy.com or Google for local gas prices, or use the AAA national average. Prices vary $1.50 or more between states, so a local number matters.
5. Enter monthly and annual mileage to project driving cost over time. The US average is about 15,000 miles per year, which is a useful default if you do not track it.

The widget returns four numbers: fuel needed for the trip, trip cost, cost per mile, and monthly fuel cost. Below that, you will see an annual fuel cost and a comparison table showing what different MPG tiers would cost per year at your current gas price.

Every fuel cost calculation comes down to dividing distance by fuel efficiency and multiplying by price. The formulas below cover one-way trips, round trips, multi-vehicle splits, cost per mile, electric vehicle equivalents, and metric (L/100km) calculations.

Core Fuel Cost Formula

Fuel Cost = (Distance ÷ MPG) × Price Per Gallon

Worked example: A 400-mile one-way drive in a sedan that gets 28 MPG, with gas at $3.60 per gallon.

Gallons used = 400 ÷ 28 = 14.286 gal
Trip cost    = 14.286 × $3.60 = $51.43

Round Trip Cost

For a round trip, multiply the one-way distance by 2 before applying the formula. Same 400-mile one-way, 28 MPG, $3.60 gas:

Round-trip distance = 400 × 2 = 800 mi
Gallons used        = 800 ÷ 28 = 28.57 gal
Round-trip cost     = 28.57 × $3.60 = $102.86

The one-way cost of $51.43 doubles to $102.86 round trip. Always check whether a published road-trip distance is one-way or already doubled before plugging it in.

Multi-Vehicle Trip and Per-Person Cost

When two or more cars travel the same route, compute fuel cost per vehicle using each vehicle's own MPG, then sum them. Split the total across everyone in both cars to get per-person cost.

Car A: 400 mi ÷ 22 MPG × $3.60 = $65.45
Car B: 400 mi ÷ 32 MPG × $3.60 = $45.00
Total trip fuel = $110.45
5 passengers total:
Per-person cost = $110.45 ÷ 5 = $22.09

If everyone carpools in one 28 MPG car instead, the trip costs $51.43 and splits to $10.29 per person. Consolidating into one vehicle roughly halves per-person fuel cost.

Cost Per Mile

$ per mile = Price Per Gallon ÷ MPG

Worked example: Gas at $3.60/gal, 28 MPG sedan.

$3.60 ÷ 28 = $0.129 per mile

That is just the fuel cost per mile. It does not include tires, maintenance, insurance, or depreciation. The IRS standard mileage rate of $0.67 per mile covers everything; fuel alone is typically $0.10 to $0.20 per mile.

EV Equivalent (Electric Vehicles)

For an EV, substitute miles-per-kWh for MPG and $/kWh for gas price:

EV Cost = (Distance ÷ miles-per-kWh) × $/kWh

Worked example: 400-mile trip in an EV that gets 4 mi/kWh, charging at $0.15/kWh (US residential average).

kWh used = 400 ÷ 4 = 100 kWh
Trip cost = 100 × $0.15 = $15.00

That is about 3.4× cheaper than the same trip in a 28 MPG gas car at $3.60/gallon ($51.43). DC fast charging at $0.35 to $0.50/kWh changes the math: the same trip at $0.40/kWh costs $40, nearly matching gas.

Metric (L/100km) Formula

Liters used = (Distance_km × L/100km) ÷ 100
Trip cost   = Liters used × Price per liter

Worked example: 600 km trip in a car rated 7.5 L/100km with fuel at €1.80/L.

Liters used = (600 × 7.5) ÷ 100 = 45 L
Trip cost   = 45 × €1.80 = €81.00

To convert MPG to L/100km: L/100km = 235.215 ÷ MPG. So 28 MPG ≈ 8.4 L/100km.

Quick Reference: Common Trip Costs at $3.60/gal

Fuel cost for popular US driving routes, one-way, at three MPG tiers:

Double these numbers for round-trip costs. A round-trip New York to DC in a hybrid runs about $40.50 in fuel, versus $81 in a 20 MPG truck.

Annual Cost Formula

Annual cost = (Annual miles ÷ MPG) × Gas price

Going from 25 MPG to 35 MPG saves $300/year at $3.50/gallon and 15,000 miles. That adds up to $1,500 over 5 years, which is relevant when comparing vehicle purchases.

The gas cost calculator number is only the starting point for a real road trip budget. Tolls, meals, lodging, and whether to drive or fly all matter for the true driving cost. This section covers the judgment calls the calculator cannot make for you.

How to Estimate Fuel Cost Without Exact MPG

If you do not know your car's exact MPG, use these class averages. They are close enough for trip cost estimates within 10 to 15 percent.

A 400-mile drive costs anywhere from $15 in a home-charged EV to $80 in a full-size pickup. The vehicle you pick for the trip matters more than the route.

Cheap vs Expensive Regions

US gas prices can vary by $1.50 or more per gallon between states. California, Washington, Nevada, and Hawaii consistently rank highest, driven by state fuel taxes and refinery constraints. Texas, Mississippi, Louisiana, and Oklahoma are consistently among the cheapest. On a 2,000-mile cross-country drive in a 28 MPG car, that $1.50 spread means $107 in fuel cost difference if you filled up entirely in one region vs the other.

Cross-border tips: Mexican gas is usually cheaper than US border-state gas, but some stations short-pour or price-switch; use major-brand stations. Canadian gas is priced in Canadian dollars per liter, so a sticker of $1.80 means roughly C$6.80/gal, or about US$5.00/gal at 0.74 exchange rate. Canadian prices are usually higher than US prices, not lower.

Tolls and Other Road-Trip Costs

Fuel rarely dominates a multi-day road trip budget. Rough rules of thumb:

• Tolls: Northeast corridor (NY to DC) runs $20 to $40 one-way in tolls on top of fuel. I-90 across the full length costs about $100 in tolls. The Pennsylvania Turnpike alone is $50+ coast-to-coast inside the state. Most Western states have zero tolls.
• Meals: Figure $15 to $25 per person per day on the road, more if you stop for sit-down meals.
• Lodging: $80 to $180 per night at midrange chains. This is almost always the largest single line item on a multi-day trip.
• Parking: Free at most destinations, but downtown hotels in major cities charge $35 to $60 per night.

On a 4-day, 2,000-mile trip, fuel at 28 MPG and $3.60 is about $257. Lodging alone (3 nights at $140) is $420, which is 1.6× the fuel bill. Meals for two people at $25/day is $200. Tolls might add $50. The true trip cost is closer to $927, with fuel at only 28 percent of the total.

When Driving Beats Flying

The rule of thumb: driving beats flying up to about 400 to 500 miles for one person, and it beats flying out to 800 to 1,000 miles for three or four people sharing a car. Flight base fare is only part of the total cost. Here is a comparison for a 500-mile trip:

For a family of four, driving a 500-mile trip one-way saves roughly $1,000 to $1,850 versus flying, before you count rental car and bag fees at the destination. Flying only starts to win decisively past 800 miles for a single traveler, or past 1,200 to 1,500 miles for a group of 3 to 4 sharing one car.