What it really costs to charge an EV at home
The usual answer to “how much does it cost to charge an electric car” is a national-average price multiplied by a battery size. That is rarely your number. Your cost depends on your utility, your rate plan, when the car draws power, and how much the rest of the house already uses that month.
Having built billing engines for electricity retailers, we think the gap between “average price” and “price of the kWh you are adding” is where most EV estimates go wrong. This calculator prices the added EV energy the way a bill would.
How this calculator works
The calculation runs in two steps: the energy the car draws from the wall, and the price of that energy on your plan.
Step 1: energy from the wall
Each vehicle model carries its EPA combined efficiency in kWh per 100 miles. EPA measures that figure at the outlet while charging on Level 2, so charging losses are already in it; in EPA’s words, “MPGe values provided by EPA include charging losses.” Nothing is added on top:
wall kWh per month = miles per month × (kWh/100 mi) ÷ 100
A car rated at 30 kWh/100 mi driven 1,000 miles a month draws 1,000 × 30 ÷ 100 = 300 kWh from the wall. The calculator uses the same EPA figure for Level 1 charging. The default mileage is 920 miles a month: about 11,000 miles a year, the average per car in FHWA’s Highway Statistics, divided by 12.
Step 2: the price of those kWh
The calculator spreads the month’s wall energy evenly over the days, starts charging each day at your chosen hour, and draws it at 7.2 kW on Level 2 (a typical home charger) or 1.4 kW on Level 1 (12 A on a 120 V outlet). It then prices the year’s bill for a typical home in your state with and without that charging. The difference is your charging cost, so every kWh lands in the right hour and the right tier:
- Time-of-use (TOU) and EV plans: a window that stays inside super off-peak is priced at super off-peak; one that spills into a shoulder or peak period is priced partly at each.
- Tiered plans: your EV energy sits on top of the home’s monthly use, so it is priced at the tier that total reaches, which can be higher than the tier the house alone would reach.
- Flat plans: a single energy price applies regardless of time.
Seasons, fixed charges and minimum bills follow the plan’s own rules in each of the 12 months.
The outputs
- Cost per full-range charge: the wall energy to drive the car’s full EPA range (range × kWh/100 mi ÷ 100) × the average price of your charging kWh. Battery capacity is not used.
- Cost per mile: monthly cost ÷ monthly miles.
- Cost per month and per year: the difference in the bill with and without the EV, averaged over the 12 months, and the year’s total.
It also runs two comparisons. Public DC fast charging is compared only when you enter a price per kWh, because no authoritative average price exists; the field starts empty. A gasoline car is priced as miles ÷ mpg × EIA’s monthly retail price of regular gasoline for your state, or for its PADD region where EIA does not publish the state. The default car gets 25.5 mpg: EPA’s Automotive Trends report puts the model year 2024 new-vehicle average at 27.2 mpg, and 1.7 mpg lower without EVs and plug-in hybrids.
Why charging time matters so much
On a TOU or EV plan, the same kWh can cost much more in the peak than overnight. How much more depends on the plan; each utility page on this site shows the exact price of every period. Some utilities put the peak in the late afternoon and evening, for example 4–9 pm, when people get home and plug in. On such a plan, start charging at 6 pm and you pay peak prices; start at midnight and you may pay the lowest price on the tariff.
Many cars and wall chargers let you schedule a start time, and on many EV plans that one setting is worth more than any other decision you make.
Charging level matters too. At 920 miles a month in a car rated 30 kWh/100 mi, a day’s charging is 276 kWh × 12 ÷ 365 ≈ 9.1 kWh. A Level 2 charger at 7.2 kW delivers that in about 1.3 hours, easily inside a cheap window. A Level 1 outlet at 1.4 kW needs about 6.5 hours, which can run into a morning shoulder or peak.
Tariff mechanics that move the result
Tiers can push EV energy into expensive territory
Tiered plans charge more per kWh once monthly use passes a baseline allowance. An EV driven 920 miles a month at 30 kWh/100 mi adds 276 kWh a month, which can be enough to push much of it into an upper tier. That is why the calculator prices EV energy as added use on top of the household, not at the plan’s first-tier rate.
Fixed charges on EV plans
Some EV plans carry a higher monthly customer charge or require a separate meter with its own fee. For a low-mileage driver, a cheap overnight rate may not recover that. Compare plans across your whole house before switching.
Winter efficiency drop
Cold weather raises consumption: the battery needs heating, cabin heat comes from the battery, and cold cells accept charge less readily. Citing a 2019 AAA study, fueleconomy.gov reports that at 20°F, EV efficiency was about 39% lower with the cabin heater on and about 8% lower with it off. The calculator uses the EPA rating all year, so if you have real winters, treat its winter-month costs as a floor.
Public charging: per kWh versus per minute
DC fast charging prices vary by network, location and time, sometimes with session fees or membership discounts, and no official average exists. That is why the calculator’s fast-charging field starts empty. Where selling electricity by the kWh is restricted for non-utilities, networks bill by the minute. Per-minute pricing penalizes cars that charge slowly: if your car accepts 50 kW, you pay the same per minute as a car taking 150 kW while receiving a third of the energy. Charging also tapers as the battery fills, so the end of a session is the most expensive part under per-minute pricing.
If you pay per minute, convert to a per-kWh price: price per minute × 60 ÷ your car’s average charging power in kW. At $0.30 a minute and a 50 kW average, that is $18 an hour ÷ 50 kWh = $0.36 per kWh. Enter the result in the calculator.
When home charging isn’t cheaper
Home charging is often the cheaper option, but not always:
- Your plan has high flat prices, or a TOU peak you cannot avoid because of your schedule.
- Your EV energy lands in the top tier of an expensive tiered plan.
- Your workplace or a retailer offers free or heavily discounted charging.
- You drive very little, and an EV plan’s extra fixed charge outweighs the energy savings.
- You would need an expensive panel upgrade to install Level 2, and the payback period is long at your mileage.
Installation costs and free workplace charging are outside the calculation, so factor those in yourself.
Frequently asked questions
Why doesn’t cost per full charge equal battery size times my rate?
Because the calculator does not use battery size. A “full charge” here is the energy from the wall to drive the car’s full EPA range: range × kWh/100 mi ÷ 100. A car with a 300-mile range rated at 30 kWh/100 mi needs 300 × 30 ÷ 100 = 90 kWh from the wall, charging losses included. That energy is priced at the average cost of your charging kWh on your plan, which reflects the hours you charge and any tier the EV pushes you into, not the plan’s headline rate.
Should I switch to an EV rate plan?
It depends on whole-house use, not just the car. Some EV plans raise peak prices for everything else in the house, so compare plans with your EV included.
Does charging to 100% cost more per kWh?
The price per kWh from the utility is the same. The calculator uses EPA’s measured efficiency and does not model how charging behaves near full.
How accurate is the gasoline comparison?
It is a fuel-cost comparison using your mpg and EIA’s latest monthly regular gasoline price for your state or region. It excludes maintenance, insurance and purchase price.
Put this calculator on your site
Free for blogs, dealers, installers and newsrooms. The embedded version uses each state’s average home price (EIA) and EPA efficiency, updates with our data, sets no cookies and shows no ads. Paste this where you want it (the small script lets the box fit its content on phones; without it the widget still works at a fixed height):
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