EV Charging Cost Calculator: How Much Does It Cost to Charge at Home?

Charging an electric car at home costs your electricity rate times the energy the car uses, plus a little lost in the charger and battery. Electricity prices vary by more than three to one between states, so the same car can cost twice as much to drive in one place as in another. This calculator uses your state’s average residential price from the EIA, or your own rate, and compares the result with a gas car.

How it works

kWh per mile   = 1 ÷ efficiency (mi/kWh) ÷ 0.90      (10% charging loss)
EV cost        = miles × kWh per mile × price per kWh
gas cost       = miles ÷ mpg × gas price
break-even     = gas cost per mile ÷ kWh per mile   (price where they match)
charge time    = kWh to add ÷ (charger kW × 0.90)

Efficiency. Most EVs get about 3 to 4 miles per kWh, according to the EPA ratings on fueleconomy.gov. Bigger trucks and SUVs get less, small cars more. If your car shows kWh per 100 miles, divide 100 by that number.

Charging loss. Some energy turns into heat in the charger, cables and battery. We use 10%, a typical figure for home charging. Level 1 and charging in cold weather can lose more.

Chargers. Level 1 is a standard 120-volt outlet at 12 amps, about 1.4 kW. Level 2 chargers on a 40-amp or 60-amp circuit deliver 32 or 48 amps at 240 volts, about 7.7 or 11.5 kW. The car’s onboard charger can limit the rate further.

Gas price. Enter what you pay locally. The default is just an example.

What it doesn’t include: public fast-charging, which usually costs several times more than home power, and the cost of the charger and installation.

Worked example

A driver in Georgia covers 12,000 miles a year in an EV that gets 3.5 miles per kWh, and charges on a 32-amp Level 2 charger. Georgia’s EIA average is 15.48¢ per kWh. Their old car got 30 mpg, with gas at $3.00.

• Energy: 12,000 ÷ 3.5 ÷ 0.9 = 3,810 kWh a year
• Charging cost: 3,810 × $0.1548 = about $590 a year, or 4.9¢ a mile
• Gas car: 12,000 ÷ 30 × $3.00 = $1,200 a year, or 10¢ a mile
• Difference: about $610 a year in favor of the EV
• Charging time: 40 miles of range takes about 1.7 hours on Level 2, or about 9 hours on Level 1

In California, at 32.58¢ per kWh, the same driving costs about $1,240 a year. With gas at $4.60, the gas car would cost $1,840, so the EV still saves about $600.

EV charging cost by state: reference table

Home charging cost at each state’s average residential electricity price, from most to least expensive, and the gas price at which a 30 mpg car would cost the same per mile.

Tips and common mistakes

Use your actual overnight rate. Many utilities have EV or time-of-use plans with much cheaper off-peak power. That can cut the cost in half compared with the state average.

Expect lower efficiency in winter. Cold weather and cabin heating can cut range by a quarter or more. Your yearly average is the right number for this calculator.

Size the circuit for the charger. Level 2 chargers are continuous loads, so a 32-amp charger needs a 40-amp circuit and a 48-amp charger a 60-amp circuit. Check that your panel has the capacity.

Mind long wire runs. A charger in a detached garage can be a long way from the panel. Check the run with our voltage drop calculator so the charger gets full voltage.

Check incentives. Some utilities and states offer rebates on chargers and installation, or special EV rates. Ask before you buy.