How do I calculate the gas cost of a road trip?

Divide the miles you will drive by your vehicle MPG to get the gallons needed, then multiply by the price per gallon. A 600-mile round trip at 28 MPG needs about 21.4 gallons, which is $94 at $4.40 a gallon.

What MPG should I use?

Use the combined MPG from the window sticker or from fueleconomy.gov for your exact model. If you have tracked your own fill-ups, your real MPG is even better because it reflects how you drive.

Why does my real gas cost differ from the estimate?

Speed, air conditioning, hills, towing, tire pressure, extra cargo and traffic all change fuel use, and prices change from station to station. Choose the driving conditions that match your route and enter the price you expect to pay.

Does driving faster use more gas?

Yes. Gas mileage usually falls quickly above about 50 mph, and the difference between 65 and 75 mph on a long trip can be 10% to 15% more gas. Steady driving with cruise control helps.

How is the electric car cost calculated?

The calculator assumes 0.30 kWh per mile and multiplies it by the miles driven and the electricity price you enter. Charging at home costs much less per kWh than public fast chargers, so a trip that relies on fast charging can cost far more than the home-charging figure.

Is this the same as the IRS mileage rate?

No. The IRS standard mileage rate is a per-mile deduction for business, medical or charitable driving and includes costs such as depreciation, insurance and maintenance. This calculator estimates gas only.

📊 Lifestyle & Travel

Gas Cost Calculator · Road Trip Fuel Budget in Miles and Gallons

Gas is the cost most people forget to price before a road trip, and it is the one that can change the most with the distance, the car and the price at the pump. This calculator turns your trip into dollars: enter the miles, your vehicle's MPG and the price of a gallon, and you see the gallons needed, the gas cost, the cost per person and how many times you will need to fill up.

It starts from the combined MPG of your vehicle and adjusts it for the way you will drive. Steady highway driving at about 60 to 65 mph saves gas, while fast highway driving, city traffic, mountains or towing a trailer, and running the air conditioning all raise fuel use. You can add tolls and parking to get the total trip cost, and split the total between the people sharing the ride.

Not everyone drives a gasoline car and many people are thinking about a change, so the calculator also prices the same trip in a 50 MPG hybrid and in an electric car using the electricity price you enter. Gas prices change every week and differ a lot by state, so treat the default price as a starting point and type in the price at stations along your route. The result is an estimate for planning, not a guarantee.

Trip Distance, One Way (miles)

Standard: 300

Trip Type

Your Vehicle Fuel Economy (MPG)

The combined MPG on the window sticker or at fueleconomy.gov

Gas Price per Gallon ($)

Use the price at stations on your route

People Sharing the Cost

Standard: 2

Driving Conditions

Air Conditioning

Tolls and Parking for the Trip ($)

Standard: 0

Fuel Tank Size (gallons)

Used to count fill-ups on the way

Electricity Price for the Electric Car Comparison ($ per kWh)

Home charging is roughly 18 cents a kWh; public fast chargers often cost 40 cents or more

Vehicle:

Fuel:

Trip:

Detailed Breakdown

10 metrics

PRIMARY RESULT

$94.29

Estimated Gas Cost

Total Trip Cost (Gas + Tolls)

$94.29

Cost per Person (2 People)

$47.14

Gallons of Gas Needed

21.4 gallons

Miles Driven

600 miles

Gas Cost per Mile

$0.157 per mile

Fill-Ups on the Way

1 stop

Range on a Full Tank

About 392 miles

Same Trip in a 50 MPG Hybrid

$52.80

Same Trip in an Electric Car

$32.40

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exploreReal-World Scenarios

When to Use This Calculator

Everyday financial situations where this tool gives you fast, accurate clarity:

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Budget a Road Trip

Know the gas bill before you leave, round trip or one way.

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Split the Cost

Share gas and tolls fairly between everyone in the car.

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Plan Your Fill-Ups

See how many stops you need and the range of a full tank.

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Compare a Hybrid or EV

See what the same trip would cost in a hybrid or an electric car.

Calculation Formula

Standard Method

Miles driven = one-way miles × 2 for a round trip Gallons needed = miles driven ÷ adjusted MPG Adjusted MPG = vehicle MPG ÷ conditions factor Gas cost = gallons needed × price per gallon Total trip cost = gas cost + tolls and parking Cost per person = total trip cost ÷ people sharing Cost per mile = gas cost ÷ miles driven Fill-ups on the way = tank fills needed − 1 (you start with a full tank) Conditions factors (extra fuel use): steady highway 0.92, typical mix 1.00, fast highway 1.15, city or heavy traffic 1.15, mountains or towing 1.25. Air conditioning on adds 10%. These are rounded planning values based on the guidance at fueleconomy.gov. Hybrid comparison: miles driven × conditions factor ÷ 50 MPG × price per gallon. Electric car comparison: miles driven × 0.30 kWh per mile × conditions factor × price per kWh. Real efficiency varies by model and weather, and public fast charging usually costs much more per kWh than charging at home.

Benchmark Example:

A round trip of 300 miles each way, 600 miles in total, in a car that gets 28 MPG with gas at $4.40 a gallon and two people sharing: • Gallons needed: 600 ÷ 28 = 21.4 gallons • Gas cost: 21.4 × $4.40 = $94.29 • Cost per person: $94.29 ÷ 2 = $47.14 • Cost per mile: $94.29 ÷ 600 = $0.157 • With a 14-gallon tank you need 1 fill-up on the way • The same trip in a 50 MPG hybrid: 12 gallons, $52.80 • In an electric car at 18 cents a kWh: 180 kWh, $32.40 If the trip is through the mountains the car uses 25% more gas: 26.8 gallons and $117.86.

Frequently Asked Questions

6 answers

Applicable Laws & Regulatory Standards

U.S. Department of Energy, EPA, EIA & IRS

Official Legal Reference

EPA & U.S. Department of Energy — Fuel Economy Guide (fueleconomy.gov)

The official source of combined, city and highway MPG for every model sold in the United States, and the guidance on how speed, air conditioning, hills, towing and stop-and-go traffic raise fuel use, which this calculator turns into its driving condition factors.

49 U.S.C. § 32908 — Automobile fuel economy labeling

Requires the fuel economy label on new vehicles, so the MPG on the window sticker is a standardized figure you can use here as your starting point.

U.S. Energy Information Administration — Gasoline and Diesel Fuel Update

Publishes the average U.S. retail price of gasoline and diesel every week. Prices change often and differ by state, so enter the price at the stations on your route.

IRS — Standard mileage rates for business, medical and charitable driving (published each year)

If you drive for work you may deduct a per-mile rate set by the IRS each year instead of actual gas costs. That rate covers more than gas, so it is not comparable to the gas-only cost shown here.

Legal citations and statutes are provided for consumer transparency, analytical validation, and educational reference under U.S. consumer financial regulations. This tool is not a substitute for formal legal, accounting, or tax counsel.

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