Edmunds: How to calculate an electric vehicle's charge costs

One of the challenges people have with electric vehicles is figuring out how much they cost to operate. The price of fully charging an electric vehicle’s battery can vary wildly depending on when and where you charge it. For the bigger picture, you should also include the amortized cost of buying and installing a home charging station and the rates your utility company charges.

Here’s how to calculate what it will cost to charge your EV, as compiled by Edmunds’ experts.

IN: KILOWATT-HOURS PER 100 MILES, OUT: MPG

When you’re shopping for a gasoline-powered car, you pay attention to how many miles per gallon it gets. For plug-in vehicles, the window sticker and the government’s fueleconomy.gov website will have a big EPA-estimated mpg equivalent figure. But this isn’t a useful metric for determining cost. A battery stores energy in kilowatt-hours, much like a gas tank stores fuel in gallons.

Instead, look for the amount of energy an electric car consumes, which is measured in kilowatt-hours per 100 miles (kWh/100 miles). This value tells you how much energy in kilowatt-hours a vehicle would use to travel 100 miles. Note that this is just the government’s estimate; your EV’s actual consumption can vary because of your driving style and environment.

COST FOR CHARGING AT HOME

The cost of electricity is more stable than the cost of gasoline, but that cost varies state by state. According to the most recent data, the residential average per kilowatt-hour ranges from 9.9 cents in Idaho to 32.3 cents in Hawaii. The national average is 13.3 cents, which is only about 2 cents more than it was a decade ago. To find your state’s average, check this state-by-state list of the average cost per kilowatt-hour.

Your state’s average is just that, however. What you pay is determined by...