How much does it cost to charge an electric car?

Electricity rates have risen dramatically across the United States over the past several months, and they’re expected to do so again. On the other hand, so have gasoline prices. So it’s a good time to ask how much does it cost to charge an electric car and how that cost compares with the cost of driving a gasoline-powered car.

In this post, we’re going to do a little math (don’t worry, not too much), using my own situation as an example, with the caveat that I live in Massachusetts, where electricity rates are among the highest in the nation. You will likely be able to save much more if you substitute our own electricity rate where appropriate.

What Do You Pay For Electricity?

For my most recent electricity bill (Sept 2022), my rate per kilowatt hour (kWh) was 35 cents. That includes both the cost of the power (supply) and the cost of getting that power to my house (delivery). Be sure to include both when calculating the cost of your own electricity.

I was able to easily calculate this rate by taking the current charges on my most recent bill and dividing that cost by the current usage. It’s important to look for the current charges, rather than simply looking for the amount due. In most cases,the two number will be the same, but not always.

That’s because the amount due could include a balance carried over from the previous month, even if you’ve paid last month’s bill. It depends on whether the payment was received before the start of the current billing cycle.

It’s also important to remember that this calculation will give you an average monthly rate. If your utility company employs a time of use tariff (i.e. charges different rates depending on what time of day you use their power). You may want to make adjustments for that.

Charging an electric vehicle overnight in those places is almost always cheaper than charging it during the day. But for now, just to keep things simple, let’s go with an average rate.

How Many Kilowatt Hours To Drive One Mile

Now let’s apply that electricity rate to the cost of charging an electric car. To do that, we need to calculate the number of miles an average electric car gets per kilowatt hour (kWh). According to the website ecocostsavings.com, the average electric car takes 0.346 kWh to travel 1 mile.

Naturally this varies depending on the electric car, but the average figure is based on the ratings of 231 vehicles that are listed on fueleconomy.gov. If you own, (or are planning to own) a specific model of electric vehicle, you can substitute your own kWh/mile number here instead.

How Much Do You Drive?

The next question to ask is how many miles you typically drive. According to the Federal Highway Administration, the average American drives 14,263 miles per year but, of course, that varies dramatically depending on where in the country you live. Californians tend to drive far greater distances than New Englanders do, and people in rural states like Wyoming are right up there, too.

As a professional sales rep, I drive considerably more than the average. You can figure out your own mileage simply by keeping track of your driving habits for a few weeks but, for now, let’s go with that national average.

14,263 divided by 12 works out at 1,188 miles per month.

Let’s Do Some Math

So now we’ve figured out the three key metrics we need:

• How much we pay per kWh of electricity ($0.35)
• How many kWh it takes to move our car one mile (3.46kWh)
• How many miles we drive on average per month (1,188 miles)

Now we take the monthly mileage of 1,188 and divide it by the 0.346 kWh per mile that the average electric car consumes. That gives us 411, which is how many kWh per month your electric car is using.

If we then take that 411kWh and multiply it by the $0.35 (35 cents) per kWh that my utility charges me for electricity and you get $144/month.

If I were to buy an electric car that gets an average number of miles per kWh and I were to drive that car as many miles as the average American does, it would cost me $144/month to charge it at my home in Massachusetts.

How Does That Compare With Gasoline?

Now let’s take those same metrics and apply them to a gasoline equivalent car. 

Between highway and city driving, my current car gets about 28 miles per gallon. If I drove the same average number of miles per month (1,188), that would mean I burn a little under 42.5 gallons of gasoline each month. (1,188 divided by 28).

The average cost of gasoline in Massachusetts is currently $3.88 per gallon (down from about $5 a gallon just a few months ago. So take 42.5 gallons and multiply it by the cost of $3.88 per gallon and that equals about $165/per month in gasoline costs.

So I could save about $21 per month by switching to an electric car. Hardly seems worth the effort, but wait. There’s more.

How to Save More

Let’s see what we can do to make the value proposition more enticing.

As stated, Massachusetts electricity rates are insanely high compared with the rest of the country. It’s quite possible (likely, even) that you are paying way less than the 35 cents/kWh that I am.

Even I could dramatically lower my own rate if I were to go solar. There are plenty of solar companies in Massachusetts that would offer me a PPA rate of 20-25 cents/kWh, provided I got the necessary sun hours on my roof..

That would lower my monthly electric vehicle charging cost to somewhere between $82/month and $103/month and increase my savings to $62-$83/month. If I were to purchase the panels outright, of course, and they could produce enough power to offset the current usage plus the EV charging (two very big “ifs”), then the cost of charging would be zero.

More Expensive Gasoline

And of course this comparison is based on gas prices that are more than 20% lower than they were just a few months ago $3.88/gallon vs $5.00/gallon). Substitute a higher gasoline price into these calculations and your savings will rise considerably.

Gasoline prices have always been very volatile, routinely rising in the summertime and seemingly subject to just about every geopolitical crisis that comes up anywhere in the world.

Electricity prices, particularly those that are contracted as part of a solar PPA) are typically much more stable, which gives you a much more predictable monthly budget for your transportation costs.

Do Your Own Math

What it all boils down to is that you have to do your own math. I can show you the average costs, and I can even break down my own costs, but won’t know how much it costs the charge an electric car at your home until you work it out for yourself.

I’ve given you the template here, all you have to do is plug in your own numbers.