CalculatorsConvertersDeveloperTextAll toolsDirectory
Submit your tool Sign in
Theme
Home/Answers/Calculators
How-to

How do I calculate how much gas will cost for a road trip?

Short answer

Divide the trip distance by your fuel economy to get the fuel needed, then multiply by the price per gallon or liter. A 400 mile trip in a car that gets 32 mpg needs 12.5 gallons, which is 45 dollars at 3.60 per gallon. A free gas cost calculator runs the numbers in your browser for any distance, economy and price.

The three numbers you need

Trip distance, your vehicle fuel economy, and the local fuel price. Distance comes from your maps app, fuel economy from your dashboard trip computer or the window sticker figure, and price from whatever stations charge along the route. Fuel cost = distance / economy x price. If you plan in metric, the same idea applies: liters used = distance in km x (L/100km figure) / 100.

Round trips and passengers

Double the distance for a round trip, and remember highway economy is usually better than the city figure, so trips skew cheaper per mile than commuting. If you are sharing the drive, a road trip calculator that divides the total by passengers shows each person share, which makes settling up painless.

Step by step

  1. Enter the distance. Type the trip distance from your maps app, doubled if it is a round trip.
  2. Enter your fuel economy. Use your car real-world mpg or L/100km figure.
  3. Enter the fuel price. Use the current price per gallon or liter where you are driving.
  4. Read the cost. The calculator shows total fuel and cost, and can split it per passenger.

Frequently asked questions

What is the formula for fuel cost?

Fuel cost = distance divided by fuel economy, times price. In metric: distance in km x L/100km / 100 x price per liter.

Should I use city or highway mpg?

For a mostly-highway trip use the highway figure or your trip computer average. City mpg will overestimate the cost.

Can I split the cost between people?

Yes. The road trip calculator divides the fuel total by the number of passengers.

Related answers