How to work out cost per mile
- Electric car. kWh per 100 miles × price per kWh ÷ 100. The kWh per 100 miles is on the EPA label and is measured at the plug.
- Gasoline car. Price per gallon ÷ miles per gallon.
- Over a year. Multiply by the miles you drive. EPA uses 15,000 miles a year on its labels.
An example at U.S. average prices
An electric car using 30 kWh per 100 miles (assumed) at the 2024 U.S. average of 16.5 cents per kWh costs 4.9 cents a mile, or $742 over 15,000 miles. A gasoline car at 30 miles per gallon (assumed) with gasoline at $3.50 a gallon (assumed) costs 11.7 cents a mile, or $1,750. The gasoline price you enter is your own: we have no gasoline price to start from.
The gasoline price at which they cost the same
For an electric car using 30 kWh per 100 miles, the break-even gasoline price for a 30 mpg car is the electric cost per mile times 30. If gasoline costs more than that where you live, the electric car costs less per mile. The table shows the five states with the lowest and the five with the highest 2024 average electricity price. The efficiency and mpg are assumed; change them in the calculator.
| State | Electricity price | Electric cost per mile | Break-even gasoline price |
|---|---|---|---|
| North Dakota | 11.51 cents | 3.5 cents | $1.04 |
| Idaho | 11.52 cents | 3.5 cents | $1.04 |
| Nebraska | 11.53 cents | 3.5 cents | $1.04 |
| Louisiana | 11.73 cents | 3.5 cents | $1.06 |
| Washington | 11.9 cents | 3.6 cents | $1.07 |
| U.S. average | 16.48 cents | 4.9 cents | $1.48 |
| Hawaii | 42.86 cents | 12.9 cents | $3.86 |
| California | 31.97 cents | 9.6 cents | $2.88 |
| Massachusetts | 29.35 cents | 8.8 cents | $2.64 |
| Connecticut | 28.75 cents | 8.6 cents | $2.59 |
| Rhode Island | 28.65 cents | 8.6 cents | $2.58 |
What cost per mile leaves out
- Public fast charging, which sets its own prices.
- The price of the car, financing and insurance.
- Maintenance and repairs.
- Rebates and tax credits.
- How the electric range and the cost per mile change with temperature and speed.