What RoadCost calculates
- Road trip gas cost (calculator): gallons of gas for the distance, the gas cost, the total with tolls, and each person's share. One way or round trip.
- Electric car trips: pick an electric car in the car list and the same calculator shows kWh and the electricity cost instead of gas.
- EV vs gas (comparison): the cost of one trip and of a year of driving for a gas car and an electric car, and the difference.
Where the data comes from
- Car fuel economy: U.S. EPA
- Combined MPG for gas cars and kWh per 100 miles for electric cars, from the fueleconomy.gov vehicle data (U.S. government data, public domain). When a model has several versions, the calculator uses their average. Hydrogen fuel cell cars are not included. You can always type your own MPG.
- Gas price: U.S. EIA
- Default $4.331 per gallon: U.S. average retail price of regular gasoline, week of Oct 12, 2026, from the EIA Gasoline and Diesel Fuel Update.
- Electricity price: U.S. EIA
- Default $0.1831 per kWh: U.S. average residential price, July 2026 (published Sep 24, 2026), EIA Electric Power Monthly, Table 5.6.A.
- Route: Mapbox
- The places you type are looked up with Mapbox geocoding, and Mapbox driving directions give the distance and drive time of the fastest route. The distance is converted from meters to miles (1 mile = 1,609.344 m) and rounded to whole miles. If no route is found, type the miles yourself.
- Local prices
- For prices near you, see AAA and type your price into the calculator.
How the cost is calculated
Gas trip
Electric car trip
EV vs gas
Drive time is the route's estimate, doubled for a round trip. Tolls are not looked up: enter what you expect to pay. Every number you enter must be above 0 (tolls can be 0), and people is a whole number from 1 to 20. All the math runs in your browser.
Worked example
A 350-mile one-way trip in a car rated 28 MPG uses 350 ÷ 28 = 12.5 gallons. At $4.331 per gallon that is 12.5 × $4.331 = $54.14. Split between 2 people, each pays $27.07. As a round trip (700 miles) the gas costs $108.28.
An electric car using 30 kWh per 100 miles needs 90 kWh for 300 miles; at $0.1831 per kWh that is about $16.48.
What the result does not include
The total covers fuel or electricity and the tolls you enter. Parking, maintenance, wear and charging fees beyond the price per kWh you enter are not part of the calculation. Real fuel use also depends on speed, load, weather and traffic, so treat the result as an estimate.