Road Trip Fuel Cost Calculator: Gas Cost, Fuel Stops and Cost per Person
Estimate the gas cost of a road trip from the distance, your car’s fuel economy (mpg, km/L, UK mpg or L/100 km) and the fuel price, one way or round trip. Split it between passengers, add tolls and parking, see how many fuel stops you need and what the trip costs if prices rise.
How it works
Total distance = one-way distance × 2 (round trip) · Fuel = distance ÷ fuel economy · Fuel cost = fuel × price · Per person = (fuel cost + tolls and other costs) ÷ people · L/100 km → mpg: 235.215 ÷ L/100 km
A road trip’s fuel bill comes down to three numbers: how far you drive, how far your car goes on a gallon (or litre), and what that fuel costs. The calculator doubles the distance for a round trip, divides it by your fuel economy to get the fuel burned, and multiplies by the price. Fuel economy can be entered in US mpg, km/L or UK mpg, or as L/100 km under More options, and the price per gallon or per litre. Highway driving at moderate speed often beats a car’s combined rating, but high speeds, roof boxes, towing, heavy loads, mountains and air conditioning all push fuel use up, so use a conservative figure for a long trip. Under More options you can add tolls, parking and other shared costs, which are included in the per-person split, and enter your tank size to see the range on a full tank and how many fuel stops to plan for, assuming you start full and refill with about a quarter tank left. The table shows how the cost changes if fuel is cheaper or dearer along the way.
Worked example
A 500-mile drive each way is 1,000 miles round trip. At 30 mpg the car burns 1,000 ÷ 30 = 33.33 gallons; at $4.29 a gallon the fuel costs $143.00, or $0.143 a mile. Split between two people it is $71.50 each. With a 14-gallon tank (420 miles of range), starting full and refilling with a quarter tank left means 2 fuel stops.
Sources: Inch Calculator: Fuel cost calculator (worked example, unit options) · Calculator.net: Fuel cost calculator (mpg, L/100 km, km/L units) · AAA gas cost calculator and national average price · EPA: MPG and Your Wallet · U.S. DOE Fact #982: fuel economy falls about 14% at 70 mph versus 60 mph
Frequently asked questions
How do I calculate gas cost for a road trip?
Divide the total miles by your car’s mpg to get the gallons, then multiply by the price per gallon. For example, 660 miles at 25 mpg is 26.4 gallons; at $3.20 a gallon that is $84.48. Double the distance first if you are driving back.
Should I use city or highway mpg for a road trip?
Most road trips are mostly highway, so the highway or combined rating is usually the better estimate. If the route has lots of climbing, headwinds, roof cargo, towing or high speeds, expect real economy to drop below the rating.
Does driving faster use more gas?
Yes. Fuel economy usually peaks at moderate speeds and falls off quickly above about 50–60 mph because aerodynamic drag grows with the square of speed. A U.S. Department of Energy summary of tests on 74 vehicles found fuel economy fell about 14% going from 60 to 70 mph and another 15% from 70 to 80 mph, so cruising at 80 instead of 65 costs roughly a fifth of your mpg.
How do you split gas money on a road trip?
The simplest fair split is the total fuel cost (plus shared tolls and parking) divided by the number of people. Enter the number of people sharing to see each share. Some groups also add a little for wear on the driver’s car.
How many fuel stops will I need?
Enter your tank size under More options. The calculator multiplies it by your fuel economy for the range on a full tank, and counts stops assuming you leave with a full tank and refill when about a quarter remains.
Can I enter liters per 100 km?
Yes. Enter it under More options as L/100 km and it replaces the fuel economy field. In the unit menu you can also choose km/L or UK mpg, and price per litre.
Related calculators
Educational estimate: real fuel use varies with speed, load, weather, terrain and traffic, and prices change along the route.