Transparent method
The formula
Worked example
Example inputs
How to interpret the result
An electric car trades a higher price for a lower running cost, and the payback is how long the saving takes to cover the premium. Driving 12,000 miles a year, a 28 mpg car at $3.50 a gallon costs about $1,500 in fuel, while an EV using 30 kilowatt-hours per 100 miles at 18 cents a unit costs about $648. The saving is about $852 a year, so a $5,000 premium pays back in about 5.9 years. Your electricity rate and how you charge move this a lot.
Before you rely on it
What to check
Use your own electricity rate and add charging losses. Public fast charging can cost several times what home charging does, which lowers the saving.
The common error
Where people go wrong with EV vs. gas fuel savings calculator
Counting only fuel. Maintenance, incentives, insurance and resale value also differ between the two cars, and they can favor either side.
Sensitivity evidence
How annual miles changes the estimated annual energy savings
| Annual miles | Estimated annual energy savings | Simple premium payback | Estimated monthly energy savings |
|---|---|---|---|
| 9,600 | $682 | 7.3 years | $57 |
| 10,800 | $767 | 6.5 years | $64 |
| 12,000worked example | $852 | 5.9 years | $71 |
| 13,200 | $937 | 5.3 years | $78 |
| 14,400 | $1,022 | 4.9 years | $85 |
Every input, tested
Which input moves the estimated annual energy savings most
| Input | Tested from | To | Estimated annual energy savings at each end | Swing |
|---|---|---|---|---|
| Gasoline price per gallon | $3.10 | $3.90 | $681 to $1,023 | $343 (40%) |
| Gas vehicle MPG | 25 | 31 | $1,032 to $707 | $325 (38%) |
| Annual miles | 10,800 | 13,200 | $767 to $937 | $170 (20%) |
| Electricity price per kWh | $0.16 | $0.20 | $924 to $780 | $144 (17%) |
| EV kWh per 100 miles | 27 | 33 | $917 to $787 | $130 (15%) |
| EV purchase-price premium | $4,500 | $5,500 | $852 to $852 | none |
Two variables at once
Estimated annual energy savings by annual miles and gas vehicle MPG
| Annual miles \ Gas vehicle MPG | 22 | 28 | 34 |
|---|---|---|---|
| 9,600 | $1,009 | $682 | $470 |
| 10,800 | $1,135 | $767 | $529 |
| 12,000 | $1,261 | $852 | $587 |
| 13,200 | $1,387 | $937 | $646 |
| 14,400 | $1,513 | $1,022 | $705 |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Annual miles | 12,000 |
| Gas vehicle MPG | 28 |
| Gasoline price per gallon | $3.50 |
| EV kWh per 100 miles | 30 |
| Electricity price per kWh | $0.18 |
| EV purchase-price premium | $5,000 |
| Estimated annual energy savings | $852 |
| Simple premium payback | 5.9 years |
| Estimated monthly energy savings | $71 |
Where the inputs come from
Annual miles, gas mileage and the gasoline price describe the gas car. For the EV, enter energy use in kilowatt-hours per 100 miles, which the EPA label lists, and your electricity price per kilowatt-hour, from your utility bill; home charging is often cheaper than public fast charging. The purchase-price premium is how much more the EV costs than the gas car, after any incentives. Use realistic annual miles.
Using the estimated annual energy savings in a real decision
Higher gas prices or cheaper electricity shorten the payback.
When the result stops applying
Charging at public fast chargers can cost several times more than home charging, and time-of-use rates change the cost. Federal EV tax credits ended for vehicles acquired after September 30, 2025, and state and utility incentives vary. Battery degradation, insurance and resale values differ between models. Cold weather reduces range and efficiency.
What to compare it with
Add running costs with the fuel cost and total cost of ownership calculators, and compare buying with leasing on the lease versus buy page. The home construction and energy categories include solar and electricity tools for charging at home. The auto depreciation calculator compares resale.
People also ask
Frequently asked questions
Is an EV cheaper to run than a gas car?
Usually per mile, especially when charging at home, though public fast charging can cost as much as gasoline. Maintenance is also typically lower.
Are there incentives for electric vehicles?
Federal credits for new EV purchases ended after September 30, 2025, but some states, utilities and cities offer rebates or reduced rates, so check locally.
How do I find an EV's efficiency?
The EPA fuel economy label lists kilowatt-hours per 100 miles. A lower number means the car uses less electricity per mile.