The cost to charge an electric car is significantly less than the cost to refuel a gas-powered car. Generally speaking, powering a car with electricity costs the rough equivalent of paying $1/gallon for gasoline in a conventional car with average gas mileage.
According to the Alternative Fuels Data Center:
The fuel efficiency of an EV may be measured in kilowatt-hours (kWh) per 100 miles. To calculate the cost per mile of an EV, the cost of electricity (in dollars per kWh) and the efficiency of the vehicle (how much electricity is used to travel 100 miles) must be known. If electricity costs $0.13 per kWh and the vehicle consumes 33 kWh to travel 100 miles, the cost per mile is about $0.04. If electricity costs $0.13 per kilowatt-hour, charging an EV with a 200-mile range (assuming a fully depleted 66 kWh battery) will cost about $9 to reach a full charge.
Using a public fast-charger will generally be more expensive because the short time to deliver the charge requires very special equipment. Charging an electric car at home is typically the most affordable option, and costs can drop even more if a customer’s electric utility offers special low overnight charging rates or charging which the utility can curtail for demand response programs.