Kelley Blue Book: How much does it cost to charge an electric car? We do the math

To answer the question of cost, we enlisted the help of John Voelcker, a longtime automotive journalist and industry analyst, who specializes in electric vehicles. He’s heard every argument that’s been made for (and against) electric vehicle ownership, including the cost of recharging compared with traditional refueling.

You need to do some math

Don’t sweat it, the math involved is pretty simple. For the most accurate estimate, it helps if you have a recent electric bill for reference. That’s because we’re kicking things off by calculating the amount you pay for electricity in a given month. In particular, we want to find out how much you spend for each kilowatt-hour of electricity used.

“For home charging, find your electric bill, then divide the [number] of kilowatt-hours you used into the bottom-line dollar total. That’ll give you the price you paid per kWh,” explains John Voelcker. “Average U.S. households pay about 12 cents/kWh, but it varies widely across the country.”

To use a simplified example, if you used 1,000 kilowatt-hours of electricity and your monthly bill is an even $100, you’re paying exactly 10 cents for each kWh. Most bills aren’t this nicely formulated and clear-cut, of course.

But for the sake of this example, let’s stick with this easy-to-use rate and apply it to a typical electric car.

What’s the cost to charge an EV in kWh?

“A conservative rule of thumb is that an electric car gets 3 to 4 miles per kWh,” Voelcker says. “So divide the total miles you drive each month by 3, to get the kWh you would use monthly. Multiply that number by your cost per kWh. The dollar amount you get will most likely be lower than what you pay each month to buy gasoline.”

To put this into perspective, let’s give an example. Let’s say you drive about 540 miles a month. For an EV, you will use 180 kWh in that time frame. Then, using the U.S. household average of 12 cents per kWh, that gets you to $21.60/month to charge an EV.

Do the numbers add up?

Again, to keep things digestible, let’s use a simple formula.

If you put 1,000 miles on your vehicle each month, for example, and pay 10 cents for each kilowatt-hour of electricity, this pegs your at-home EV recharging bill at $25 to $33 dollars a month (based on the calculation of 3-4 driving miles equaling one kilowatt-hour). Even if you double your electric rate to 20 cents per/kWh, your EV recharging cost will be $50 to $66 dollars.

How does the recharge cost compare to a fuel fill-up?

With the average price of gas hovering around $2.83 as of this writing, according to AAA, filling up a 12-gallon gas tank currently costs about $33.96. Things get a little tricky at this point because, as we all know, cars and trucks use vastly different amounts of fuel.

Let’s say you’re driving an economical car that has a combined average of 30 miles per gallon during a mix of city and highway driving. Using that same 12-gallon tank as a reference point, you’ll have 360 miles of driving range for each fill-up. If you’re driving the same 1,000 miles a month, you’ll need to refuel at least three times each month and spend about $101.88.

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Again, this only an estimate, since fuel prices and mileage are so variable. But considering few cars and SUVs come anywhere close to delivering a 30-mpg combined average, our fairly conservative number-crunching in this scenario makes it clear that recharging will cost less than keeping a car refueled. The financial gap narrows with a more fuel-efficient car, but it still remains.

Charge an EV at home

Electricity rates are subject to many factors, including the region where you live, the time of year, and even the time of day when peak charges apply. For the most part, electricity usage and costs are at their lowest late at night. That’s good news for anyone considering an EV, according to John Voelcker.

“While shoppers worry about access to public charging stations, they need to know that as much as 90% of electric-car charging is done overnight at home,” Voelcker explains. “The cheapest way to charge your electric car is almost always at home, overnight. Some utilities have special low rates for the overnight period when their demand is lightest.”

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Where you live directly impacts your electric bill. On average, in February of this year, people living in New England states (including Massachusetts, New Hampshire, Connecticut, and Rhode Island) paid roughly double for each kWh of energy used than those living in states like Texas, Nevada, Colorado, and Tennessee.

The cost of Level 2 and faster charging

When talking about public Level 2 charging and Level 3 fast-charging systems, the prices are harder to narrow when compared with standard at-home costs. That’s because charging networks vary in price, not to mention availability around the country.

You can always opt to have a Level 2 charger installed in your garage. The cost isn’t cheap. It’s about $2,000 for parts and installation is a reasonable ballpark figure. Moving up to Level 2 means you’ll more than halve your charge time. That can potentially add value to your home.

“Every electric car (Tesla included) can use public Level 2 stations,” says John Voelcker, “but Nissan NSANY, +1.07% Leafs use one fast-charging standard (called CHAdeMO) while every other EV uses a different fast-charging standard called CCS.”

Finding the right plug to charge an EV

Voelcker explains the difference sounds more complex than it is. “The vast majority of fast-charging locations have both kinds, with a different cable on each side of the station. It’s like the same gas pump could dispense both regular gasoline and diesel fuel from different hoses.”

As for the price, a 240-volt (Level 2) recharge could cost you anywhere from zero dollars to a fixed hourly rate. Charging networks often provide membership programs to minimize your recharge cost. That’s something especially useful if you can’t regularly charge your vehicle at home.

Voelcker singled out one such example, for comparison’s sake. “The EVgo network charges $1.50 per hour for Level 2 charging at up to 7.2 kilowatts. That’s the standard plug on most charging stations.”

Checking the company’s website, a pay-as-you-go approach, and monthly membership both permit 45-minutes of (Level 3) fast-charging. This is the quickest approach to charging your electric car but, as Voelcker points out, “fast charging is more expensive than Level 2 charging because you can’t do it at home.”

The faster the charging, the higher the rate

These units, unlike a typical 240-volt Level 2 home recharging system, are prohibitively expensive for a private individual to have installed. Tesla TSLA, +2.05% has its own dedicated Supercharger network but, once again, the rates can vary widely depending on region, timing, the model of Tesla being charged, and even if you choose Tier 1 or Tier 2 recharge speeds (the latter being quick but more expensive). One important caveat: Tesla Superchargers only work for Tesla vehicles.

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Voelcker again stresses that home charging is the best option for anyone considering an electric car Yet, equally important is knowing where to find EV perks that are close to home. “Some workplaces offer charging for employees’ cars…But electric-car owners quickly learn which public stations near them are free, which charge for charging and how much they cost.”

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For example, a bustling parking lot in a crowded city-center might lure EV owners with the promise of free recharging. But the resultant fee for parking there could easily zoom past what you’d have paid to fill up even the thirstiest fuel-hog car or truck.

Voelcker’s final words of advice to EV owners: “Always ask before plugging in!”

This story originally ran on KBB.com.