How to estimate road-trip fuel cost
Estimating fuel cost for a road trip comes down to three numbers: how far you're driving, how efficient your vehicle is, and the price of fuel. The formula is simple:
Add tolls for the total, then divide by the number of travelers to get the cost per person.
If you're driving there and back, tick Round trip to double the distance. Working in metric? Switch the units toggle to kilometers — fuel economy becomes litres per 100 km and price becomes per litre, and the math is converted for you.
Gas vs EV: which is cheaper per mile?
An electric vehicle's "fuel" cost depends on how many miles it travels per kWh and what you pay for electricity. Divide the distance by miles-per-kWh to get the energy used, then multiply by your price per kWh.
Charging at home on a standard residential rate is usually dramatically cheaper per mile than burning gasoline. The gap narrows — and can even flip — when you rely on public DC fast chargers, which often charge a premium per kWh. The comparison block above shows the dollar difference for the exact trip and prices you enter, so you can see which option wins for you.
Gas vs EV: cost per 100 miles
| Vehicle | Cost per 100 miles |
|---|---|
| 25 MPG gas | $14.00 |
| 35 MPG gas | $10.00 |
| 50 MPG hybrid | $7.00 |
| EV at 3 mi/kWh | $5.33 |
| EV at 4 mi/kWh | $4.00 |
Assumes $3.50/gallon and $0.16/kWh — real costs vary with prices, terrain and charging.
Frequently asked questions
- How do I calculate gas cost for a road trip?
- Divide the total trip distance by your vehicle's MPG to get the gallons needed, then multiply by the price per gallon: cost = (distance ÷ MPG) × price. A 280-mile trip in a 28 MPG car uses 10 gallons; at $3.50 that's $35, plus any tolls.
- How much does it cost to charge an EV for a road trip?
- Divide the distance by your EV's miles-per-kWh to get the energy used (kWh = distance ÷ efficiency), then multiply by your electricity price per kWh. A 280-mile trip at 3.5 mi/kWh uses 80 kWh; at $0.16/kWh that's about $12.80, before any public fast-charging premiums.
- Is an EV cheaper than gas for road trips?
- Usually yes when charging at home or on cheap power, where cost per mile is well below gasoline. Public DC fast charging often costs more per kWh and can narrow the gap. Enter your own numbers above to see which is cheaper for your trip.
- How do I split fuel costs between travelers?
- Add up the total fuel cost plus any tolls, then divide by the number of people sharing the ride. The calculator does this automatically and shows the per-person figure.
- What MPG should I use?
- Use your car's real-world combined fuel economy, which is often a bit below the EPA sticker number. If unsure, check your trip computer's long-term average for a realistic figure.
- How much gas for a 500-mile trip?
- Divide 500 by your MPG: a 25 MPG car needs 20 gallons, a 40 MPG car needs 12.5 gallons. Multiply the gallons by your price per gallon to get the cost.
- Does driving fast or running AC use more fuel?
- Yes. Higher highway speeds dramatically increase aerodynamic drag, and running the air conditioning adds load on the engine — both lower your effective fuel economy.