Worked example: a 300-mile road trip for four
- Round trip: 300 miles × 2 = 600 miles
- Fuel: 600 miles ÷ 30 MPG = 20 gallons
- Fuel cost: 20 gallons × $3.50 = $70.00
- Add $20 in tolls and parking: $90.00 for the trip
- Split four ways: $22.50 each
At an average of 60 mph the driving takes 10 hours, not counting stops. The 20 gallons of gasoline put out about 178 kg (392 lb) of CO2 from the tailpipe. Change any number in the calculator to see your own trip.
Splitting gas money with passengers
Most groups split one of two ways. Either everyone in the car pays an equal share, driver included, or the passengers cover the fuel and the driver pays nothing, since they're already putting miles and wear on their car. Set "People splitting the cost" to match whichever you agree on.
Decide before you leave whether tolls, parking and shared rooms go into the split. If some costs only apply to part of the group, leave them out of the calculator and settle them separately.
Planning the drive
- Distance: take it from a map app for your actual route. Detours and side trips add up, so round up.
- Fuel economy: highway MPG suits long interstate stretches. A loaded car, a roof box or mountain roads will use more.
- Price: prices change from state to state. Use what you expect to pay along the way.
Last reviewed: October 4, 2026.
How the trip cost is calculated
Trip cost = (distance ÷ fuel economy × price) + other costs
The fuel part uses the total distance, one way or both ways. Other costs are the totals you enter for tolls and parking, lodging, and food. Cost per person is the trip cost divided by the number of people splitting it.
Drive time, fuel stops and CO2
Drive time is the total distance divided by your average speed, so it leaves out stops. Fuel stops assume you start with a full tank: the fuel the trip needs divided by your tank size, rounded up, minus one. The CO2 figure multiplies the fuel burned by the EPA's tailpipe figures of 8,887 grams of CO2 per gallon of gasoline and 10,180 grams per gallon of diesel.
Cedrick Reese put this page together to answer the question he kept asking before long drives: what will the whole trip cost, and what's everyone's share? Fuel uses the same distance ÷ fuel economy × price formula as the site's main calculator, and the CO2 factors come straight from the EPA's published figures for gasoline and diesel. Results are checked against worked examples like the 300-mile trip above, and the car picker's EPA ratings are rebuilt from the fueleconomy.gov dataset whenever it's refreshed. Lodging and food are your own numbers, so the site doesn't suggest budgets for them.
Trip cost questions
How do I calculate how much a road trip will cost?
Work out the fuel first: divide the total miles by your MPG, then multiply by the price per gallon. Then add the costs you'll pay along the way, such as tolls, parking, lodging and food. Divide the total by the number of people if you're splitting it.
How much gas money should each passenger pay?
The simplest fair split is the fuel cost divided by everyone in the car, driver included. Some groups leave the driver out, since they're already covering wear on their car. Enter the number of people who are paying, and the calculator shows each person's share.
Does the drive time include stops?
No. Drive time is the distance divided by the average speed you enter, so it covers time behind the wheel only. Add your own time for fuel stops, meals and rest breaks.
How is the CO2 for a trip worked out?
The calculator multiplies the fuel the trip burns by the EPA's figures of 8,887 grams of CO2 per gallon of gasoline and 10,180 grams per gallon of diesel. It covers tailpipe CO2 only.
How many fuel stops will I need?
Enter your tank size and the calculator divides the fuel the trip needs by one tank. If you start with a full tank, the number of stops is that figure rounded up, minus one. Most drivers refill before the tank is empty, so plan for one more.
CO2 source: EPA, Greenhouse Gas Emissions from a Typical Passenger Vehicle.
More fuel tools
For a quick fuel-only figure, gallons tables and cost per mile, use the fuel cost calculator. To see what you spend on fuel across a whole year, try the gas budget calculator.
Choosing which car to take? Compare fuel costs between two vehicles or look up any car's MPG on our sister site, GasMileageCalculators.com.
Still deciding how to go? The drive or fly calculator compares gas against airfare for your group. Running the AC all trip? See how much it costs.