EV Home Charging Cost Calculator
Work out the cost to charge an EV at home from battery size, state-of-charge range, charger efficiency, and your electricity price — plus cost per mile vs petrol. Free.
EV Home Charging Cost Calculator
Charging at home is where EVs save the most money. Enter your battery size, how far you're topping up, your charger's efficiency, and your electricity rate to see the cost of a charge, the cost per mile, and how it compares to running a petrol car.
How to Use the EV Charging Cost Calculator
Enter your battery and charge range
Your battery's usable capacity in kWh, and the state-of-charge you're charging from and to. Most owners cycle in a daily band (often 20–80%) to protect battery longevity rather than charging to 100%.
Set charger efficiency
Some energy is lost as heat between the wall and the battery. The U.S. Department of Energy says battery charging efficiency is often 84% to 93%; the default is 90%. This is why your meter shows more kWh than ends up in the battery.
Enter your electricity price
Use your per-kWh rate — and if you're on a time-of-use plan, the off-peak overnight rate, since that's when most home charging happens and where EVs save the most.
Compare to petrol
Enter your EV's efficiency from its EPA label in miles per kWh (100 ÷ the label's kWh per 100 miles), and a petrol car's price and mpg, to see the per-mile cost gap. The EPA measures that rating at the outlet, so it already includes charging losses, and the calculator applies it to the energy drawn from the grid.
What It Really Costs to Charge an EV at Home
Energy In, Losses, and Cost
The cost of a home charge comes down to three numbers: how much energy you put in the battery, how much extra the grid delivers to cover charging losses, and what you pay per kilowatt-hour. The energy added to the battery is just your battery's capacity multiplied by the percentage you're charging — topping a 75 kWh battery from 20% to 80% adds 45 kWh. But the meter sees more than that, because charging isn't perfectly efficient: the U.S. Department of Energy puts battery charging efficiency at often 84% to 93%, so at 90% the grid supplies 50 kWh to put 45 kWh into the battery. Multiply that grid figure by your electricity rate and you have the true cost of the charge. At 16 cents per kWh, that 45 kWh top-up costs about eight dollars, and a car rated 3.5 miles per kWh gets about 175 miles from it.
The headline EV value proposition lives in the cost per mile. Divide the charge cost by the miles that charge buys you, and home-charged electricity typically works out to a small fraction of what petrol costs per mile. An EV rated 3.5 miles per kWh on 16-cent power costs about 4.6 cents a mile, against about 11.7 cents a mile for a 30-mpg petrol car at $3.50 a gallon: about $710 less every 10,000 miles at those prices. A cheaper overnight time-of-use rate widens the gap; paying public fast-charging prices narrows it, so the price you pay per kWh is the number that decides the comparison.
"An EV's cost per mile is just the price of a kilowatt-hour divided by the miles it buys. Where you plug in sets the first number."
What Moves the Cost, and the Global Picture
Two things move the result most. The first is the price per kWh: many utilities offer cheaper overnight time-of-use or EV tariffs, and because cost per mile is the price divided by miles per kWh, a rate half the price gives a cost per mile half as large. The second is the efficiency figure: use the EPA label's, which includes charging losses, or your own measured miles per kWh at the meter. Daily charge limits are a battery-care question for your owner's manual, not a cost question; the price per kWh is the same at 80% or 100%. The same arithmetic applies anywhere, only the rates and units change: in the United Kingdom and Europe you'd enter pence or euro-cents per kWh, and convert litres and L/100 km to a per-mile figure for the petrol comparison. Wherever you are, the method is identical: figure the grid energy including losses, multiply by your rate, and compare the per-mile result to what the pump costs.
The EPA rating is measured at the outlet, charging losses included
Energy added = battery capacity × the % you charge (20→80% of 75 kWh = 45 kWh).
DOE puts battery charging efficiency at often 84% to 93%, so the grid supplies more than the battery receives.
Charge cost = grid energy × your price per kWh.
At 16¢/kWh and 3.5 mi/kWh an EV costs 4.6¢ a mile; a 30-mpg car at $3.50 costs 11.7¢.
EV cost per mile = price per kWh ÷ miles per kWh (EPA rating).
A Level 2 home charger delivers 2.9 to 19.2 kW (DOE AFDC).
Level 1 (a standard outlet) at about 1.9 kW adds roughly 5 miles of range an hour (DOE AFDC).
The EPA label states energy use in kWh per 100 miles: mi/kWh = 100 ÷ that figure.
Cold weather cuts efficiency — winter range and cost per mile both worsen.
The EPA rating is measured at the outlet, so it already includes charging losses.
Frequently Asked Questions
- Multiply the energy you add to the battery by your electricity rate, then add charging losses. Charging a 75 kWh battery from 20% to 80% adds 45 kWh; with 90% charging efficiency the grid supplies about 50 kWh, so at 16¢/kWh the charge costs about $8, and a car rated 3.5 mi/kWh gets about 175 miles from it. Your exact cost depends on your battery size, charge range, and per-kWh price — enter them above for a precise figure.
- Charging isn't perfectly efficient. Energy is lost as heat in the charging cable, the car's onboard charger, and the battery itself, so some of the electricity you pay for never reaches the battery. The U.S. Department of Energy says battery charging efficiency is often 84% to 93% — the default 90% here means you pay for about 11% more energy than the battery gains. That's why your electricity meter shows more kWh than the car's display says was added.
- It depends on the two prices. An EV rated 3.5 miles per kWh on 16¢ electricity costs about 4.6¢ a mile, while a 30-mpg petrol car at $3.50/gallon costs about 11.7¢ a mile: about $710 less per 10,000 miles. Halve the electricity price and the EV's cost per mile halves too; pay more per kWh at a public charger and the gap narrows.
- Follow your owner's manual: many EVs let you set a daily charge limit below 100%, and the manual says what the manufacturer recommends for your battery. The cost per kWh is the same either way. This calculator defaults to 20–80% simply as an example range; enter whatever range you actually charge.
- It's an EV's efficiency — how far it travels on one kilowatt-hour of energy, the electric equivalent of miles per gallon. The EPA label gives it as kWh per 100 miles, measured at the outlet, so it includes charging losses; divide 100 by that figure for miles per kWh. Higher miles per kWh means a lower cost per mile. A car's trip computer may report energy used from the battery instead, which does not include charging losses, so its figure is not directly comparable.
- Yes, indirectly. Cold reduces an EV's efficiency (fewer miles per kWh) because of battery chemistry and cabin heating, and it can slow charging and increase losses. The price per kWh doesn't change, but you'll need more energy for the same distance in winter, raising the effective cost per mile. To model winter, lower the miles-per-kWh figure you enter — dropping from 3.5 to 2.8, for example, raises your cost per mile accordingly.
- Almost always. Public fast-charging prices are usually higher per kWh than home electricity, and the cost per mile rises in proportion; enter the public price to see the effect. Public charging buys convenience and speed for trips, but routine charging at home (especially on an off-peak rate) is where EVs save money. This is why access to home or workplace charging is the strongest predictor of whether an EV will be cheap to run for a given owner.
- Time-of-use (TOU) or dedicated EV tariffs charge different rates by time of day, with cheap overnight prices when grid demand is low. Since cost per mile is the price per kWh divided by miles per kWh, charging in a cheaper off-peak window cuts the per-mile cost by the same proportion as the price. Many utilities offer special EV plans. Enter your off-peak rate in the calculator to see the savings — it's often the single biggest lever on EV running costs after simply having home charging at all.
- Yes — the energy math is universal. Enter your local electricity price per kWh (pence or euro-cents in the UK/EU, and so on) and, for the petrol comparison, your local fuel price and your car's economy. If you measure fuel in litres and economy in L/100km, convert to a per-mile or per-km basis to compare. EV adoption is rising fast across Singapore, Thailand, Indonesia and beyond; the calculator's method applies wherever you plug in — just use your own rates.
- It depends on your charger's power. The DOE's Alternative Fuels Data Center puts Level 2 units at 2.9 to 19.2 kW; at 7 kW, drawing 50 kWh from the grid takes about seven hours, easily done overnight. A standard outlet (Level 1) is assumed at 1.9 kW and adds roughly 5 miles of range per hour of charging. This calculator focuses on cost rather than time, but charging speed is why most owners plug in at night and wake up full.
Method & sources
How it computes
Battery energy = capacity x (to - from)%; grid energy = battery energy / charging efficiency; cost = grid energy x price. Miles = grid energy x the EPA rating in mi/kWh, which is measured at the outlet and so includes charging losses; EV cost per mile = price / mi/kWh. Petrol cost per mile = price / mpg. EnergyKernel.evCharge, tested.
What this tool implements
- Bug fixed: the page multiplied the EPA efficiency rating by the energy that reached the battery. EPA measures that rating at the electrical outlet, so it already includes charging losses (76 FR 39478); the loss was counted twice, understating miles and overstating cost per mile by 1/efficiency: 5.1 cents instead of 4.6 at the page's defaults.
- Corrected against DOE: charging losses were given as '8-15%' and Level 2 efficiency as '85-92%'; fueleconomy.gov gives battery charging efficiency as often 84% to 93%. Charging power and range per hour now follow DOE's Alternative Fuels Data Center (Level 1 about 1.9 kW, about 5 miles per hour; Level 2 2.9 to 19.2 kW).
- Removed as unsourced: public fast charging at '3-5x' the home rate, time-of-use rates that 'roughly halve' cost per mile, '2.5-4.5 mi/kWh' for most EVs, and 'most manufacturers recommend 80%'.
Sources
- U.S. Environmental Protection Agency and Department of Transportation. Revisions and Additions to Motor Vehicle Fuel Economy Label, final rule, 76 FR 39478 (6 July 2011): EV energy measured at the electrical outlet, including charging losses. https://www.federalregister.gov/d/2011-14291
- U.S. Department of Energy, fueleconomy.gov. All-Electric Vehicles: battery charging efficiency often 84% to 93%. https://www.fueleconomy.gov/feg/evtech.shtml
- U.S. Department of Energy, Alternative Fuels Data Center. Charging Electric Vehicles: Level 1 (1.9 kW, about 5 miles of range per hour) and Level 2 (2.9 to 19.2 kW) equipment. https://afdc.energy.gov/fuels/electricity-stations
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