Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate the estimated gas cost for a trip from distance, fuel economy, and price per gallon.
This tool calculates (distance ÷ MPG) × price per gallon to estimate how much gas a trip will cost, given your vehicle's real-world fuel economy and the current price per gallon.
Enter your trip distance, your vehicle's MPG, and the price per gallon. Your estimated gas cost appears instantly.
The calculator first finds how many gallons the trip will use by dividing distance by your miles per gallon, and then multiplies the gallons by the price per gallon. If the MPG field is zero or negative, the tool returns zero rather than an error. The result assumes a constant fuel economy across the whole distance, which is a simplification of real driving.
Gas cost = (distance / MPG) x price per gallon
Suppose you plan a 300 mile trip in a car that gets 28 MPG and the fuel price is 3.50 dollars per gallon. The trip needs 300 / 28, or about 10.71 gallons. Multiplying by 3.50 gives roughly 37.50 dollars. If the same car averages only 24 MPG because of highway speed, a roof box, and a full load, gallons rise to 12.5 and the cost to about 43.75 dollars. That difference of about six dollars on a single trip is a good reminder to enter a realistic MPG rather than the best rated figure.
Use the total miles you will actually drive. For a round trip, enter the full round-trip distance, not one way. Add extra miles for detours, local driving at the destination, and getting to and from the highway. A navigation app can give the route distance, and you can add a small margin for side trips.
Fuel prices differ between stations and regions and change from week to week. Check current prices along your route rather than relying on an old number. If you will refuel in several places, use an average of the prices you expect. For very long trips through different regions, the Road Trip Gas Cost Calculator lets you also split the cost between travelers.
The result is an estimate for planning, and your actual spend will vary with driving conditions.
Your dashboard's trip computer (if equipped) or the Miles Per Gallon Calculator, using your own recorded miles driven and gallons used, will be more accurate than a manufacturer's rated MPG for your actual driving conditions.
Enter whichever distance you will actually drive in total. For a round trip, include both directions.
Real fuel economy changes with speed, load, weather, and traffic, and prices vary by station. The tool uses a single MPG and a single price for the whole trip.
Yes, as long as you enter the vehicle's MPG and the diesel price per gallon. The math does not depend on fuel type.
The tool returns zero instead of dividing by zero. Enter a positive MPG value to get a meaningful cost.
Reference: EPA Fuel Economy