Gas Trip Cost Calculator

Estimate the fuel cost of a trip from distance, your vehicle MPG, and the price of gas — with multi-leg trips and a round-trip option.

Inputs

Miles for the trip. For a multi-stop trip, list each leg separated by commas (e.g. 120, 85, 200).

Your vehicle's miles per gallon (US).

Price per US gallon of fuel.

Double the distance for there-and-back.

Result

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How to use this calculator

  • Enter the trip distance in miles (or list each leg, comma-separated, for a multi-stop trip).
  • Enter your vehicle's MPG and the price of gas per gallon.
  • Choose one-way or round trip.
  • Read the estimated fuel cost, gallons needed, and cost per mile.

About this calculator

Planning a road trip? This calculator estimates how much you will spend on fuel from three numbers: the distance you will drive, your vehicle's fuel economy in miles per gallon, and the current price of gas. It divides the distance by your MPG to find the gallons you will burn, then multiplies by the price per gallon. You can add up a multi-stop trip by entering each leg separated by commas, and tick the round-trip option to double the distance automatically. The result includes the total gallons, the dollar cost, and a handy cost-per-mile figure for comparing routes or vehicles. For the most realistic estimate, use your real-world highway MPG rather than the optimistic EPA combined figure, since most road-trip miles are at higher, less efficient speeds.

How it works — the formula

Gallons = Distance ÷ MPG Cost = Gallons × Price per gallon Cost/mile = Cost ÷ Distance

Distance over fuel economy gives the fuel volume required; multiplying by unit price gives the total. Round trip simply doubles the distance before the division.

Source: US DOE/EPA — fueleconomy.gov

Worked examples

Example 1
300 mi, 25 MPG, $3.50/gal
Inputs:
distance=300, mpg=25, price=3.50
Output:
12 gal × $3.50 = $42.00
Example 2
1000 mi, 30 MPG, $4.00/gal
Inputs:
distance=1000, mpg=30, price=4.00
Output:
33.33 gal × $4.00 = $133.33
Example 3
Round trip 250 mi, 20 MPG, $3.00
Inputs:
distance=250, mpg=20, price=3.00, roundTrip=yes
Output:
500 ÷ 20 × $3.00 = $75.00

Limitations

  • Assumes constant MPG and a single gas price for the whole trip.
  • Does not model elevation, load, or speed effects on economy.
  • Liquid fuel only — not for electric vehicles.

A planning estimate; real fuel spend varies with conditions and price changes en route.

Frequently asked

How do I calculate the gas cost of a trip?+
Divide the trip distance by your MPG to find gallons needed, then multiply by the gas price. For 300 miles at 25 MPG with $3.50 gas: 300 ÷ 25 = 12 gallons, × $3.50 = $42.00.
Should I use city or highway MPG?+
Use the figure that matches your trip. Long road trips are mostly highway, so use highway MPG (or your measured real-world number). For around-town errands, city MPG is more accurate. The combined EPA rating is a blend of both.
How do I handle a multi-stop trip?+
Enter each leg's distance separated by commas and the calculator sums them. For example "120, 85, 200" totals 405 miles. Use the round-trip option only if you are returning along the same total distance.
What is cost per mile?+
It is the fuel cost divided by the distance — how much each mile of driving costs in gas. It is useful for comparing two routes of different length, or two vehicles, on an equal footing. At $42 for 300 miles, that is $0.14 per mile.
Why might the real cost be higher?+
Higher speeds, mountainous terrain, headwinds, a roof box or heavy load, air conditioning, and idling in traffic all lower MPG and raise cost. Gas prices also rise and fall along a route, so budget a margin above the estimate.
Does this work for electric vehicles?+
No — this is for liquid fuel priced per gallon. For an EV, use cost = (distance ÷ miles-per-kWh) × electricity price per kWh, or a dedicated EV cost calculator.

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