How this calculator works
Enter the distance, your car’s fuel economy and the price of gas, and you’ll get the total cost of the trip, the cost per person and per mile, the gallons you’ll need and the CO2 you’ll emit. Turn on round trip to double the distance, and add tolls or parking as extra costs.
The second tab compares two cars on the same trip, the quickest way to answer “would a hybrid or an EV actually save me money?”
The formula
gallons = miles ÷ mpg and cost = gallons × price per gallon
A 300-mile trip in a car that gets 30 mpg uses 10 gallons. At $3.20 a gallon, that’s $32.00, or about 10.7 cents a mile. There and back with four people in the car, it’s $64, which is $16 each.
Your mpg matters more than the gas price
The same 300 miles at $3.20 a gallon:
| Fuel economy | Gallons | Cost |
|---|---|---|
| 25 mpg | 12 | $38.40 |
| 30 mpg | 10 | $32.00 |
| 35 mpg | 8.6 | $27.43 |
Use the mpg your dashboard shows over a few tanks if you can: the EPA rating on the window sticker is a good start, but real-world numbers are often lower at highway speeds or with a loaded car.
Premium gas only makes sense if your owner’s manual requires it. The same trip in a car that gets 28 mpg on premium at $4.00 a gallon costs $42.86.
Gas vs. electric
Electric cars are rated in kWh per 100 miles, the figure on their EPA label. An EV that uses 30 kWh per 100 miles needs 90 kWh for the same 300-mile trip: $15.30 at $0.17 per kWh, a typical home electricity price.
Over a year of 12,000 miles, the 30-mpg gas car spends $1,280 on fuel and the EV $612: $668 a year less. That assumes home charging; public fast chargers often cost two or three times as much per kWh, so on long road trips the savings shrink. Try your own numbers in the comparison tab.
Emissions
Burning a gallon of gasoline releases about 19 pounds of CO2, so the 300-mile trip at 30 mpg emits roughly 193 pounds. Diesel emits more per gallon but usually burns fewer gallons for the same distance.
How to spend less on gas
- Slow down on the highway. Fuel economy drops quickly above 50 to 60 mph.
- Keep your tires properly inflated. Underinflated tires waste fuel and wear out faster.
- Travel light. Roof boxes and extra weight cost you mpg on every mile.
- Shop around for gas. Prices can vary by 20 or 30 cents a gallon within a few miles.
Gas is only part of what a car costs. To add up depreciation, insurance and everything else, try the car cost calculator.