How Much Does It Cost to Charge an EV at Home? Count the Losses

2026-10-15

How much does it cost to charge an EV at home? Multiply the energy your car draws from the wall by your price per kWh. That's more than the energy that ends up in the battery, because some is lost as heat while charging. Take a 75 kWh battery charged from 20% to 80% at 17 cents per kWh with 90% charging efficiency. It puts 45 kWh into the battery, draws 50 kWh from the grid and costs $8.50.

Most guides in the search results stop at "battery size times price per kWh". That shortcut skips two things. It ignores charging losses, so it comes out too low. And it assumes every session runs from empty to full, which few drivers do. This guide fixes both, then shows the opposite mistake people make with cost per mile.

How much does it cost to charge an EV at home: the formula

The calculation has three steps, and each one uses a number you can find on your car's display or your bill.

• Energy added = usable battery capacity × (target charge − current charge). From 20% to 80% of 75 kWh, that's 45 kWh.
• Energy from the grid = energy added ÷ charging efficiency. At 90%, the 45 kWh needs 50 kWh from the wall.
• Cost = energy from the grid × price per kWh. At 17 cents, that's $8.50.

The 5 kWh between 45 and 50 is the charging loss. You pay for it, and your meter counts it, but it never reaches the battery. With the same inputs, a full charge from 0% to 100% comes to $14.17.

Use the usable (net) capacity, not the gross figure from a spec sheet. The car only lets you fill the usable part, so that's the part you pay to fill.

Why battery size times price comes out too low

Energy is lost in the charger, the cables and the battery itself. The Department of Energy's FuelEconomy.gov puts typical charging efficiency at 84% to 93%. Its breakdown of where an EV's energy goes shows charging losses of about 10% in combined driving.

Even the Department of Energy's own home-charging page skips losses in its quick example. A 54 kWh battery charged from empty at 10.7 cents per kWh "will cost about $6", which is battery size times price. That's fine as a ballpark, but your meter will show more than 54 kWh.

The way you add losses matters a little too. Some calculators add 10% to the battery energy. The DOE and the German auto club ADAC define the loss as a share of the energy taken from the wall. With that definition, you divide by efficiency instead. At 90%, 1 kWh in the battery takes about 1.11 kWh from the wall, not 1.10. The gap is only about 1%, but dividing matches how the losses are actually measured.

Losses depend on how you plug in

There's no single loss figure, because the charging method changes it. The most detailed recent data comes from ADAC, which published charging-loss measurements in August 2026.

• 11 kW wallbox: losses of about 5% to 7%.
• Ordinary household socket: about 13% to 24%. The car's charging-control electronics draw 100 to 300 W the whole time it's plugged in, and at low power the session lasts many hours.
• DC fast charging: 5% to 15%, and more in cold weather when the battery is heated.

An older Idaho National Laboratory test of a Chevrolet Volt charger points the same way: 90.8% efficiency on Level 2 and 88.8% on Level 1. The ADAC socket tests were done on German 230 V outlets, so treat them as a guide to the direction of the effect, not as a number for a US 120 V outlet.

To see what efficiency means in money, look at 80%. At that efficiency, one fifth of the energy you pay for turns into heat instead of driving range. If you charge from a regular outlet, lower the efficiency in your estimate. Keep 90% for a wallbox.

Cost per mile: don't count the losses twice

Here the mistake runs the other way. For cost per mile or per 100 miles, use the rated consumption on the EPA label or on fueleconomy.gov, in kWh per 100 miles. FuelEconomy.gov states that this electricity use is measured from the charge source. The losses are already in it. WLTP figures, used in Europe, include charging losses too.

So cost per 100 miles is simply rated kWh/100 mi × price. Some calculators divide the rated figure by charging efficiency as well, which counts the same losses twice. In our calculator, changing efficiency from 50% to 100% leaves the cost per 100 miles where it is. At 30 kWh/100 mi and 18.34 cents, it's $5.50 either way.

At the June 2026 US average of 18.34 cents per kWh, typical ratings give:

• 24 kWh/100 mi, the rating of a Tesla Model 3 Standard RWD in the 2026 EPA guide: $4.40 per 100 miles.
• 30 kWh/100 mi, a mid-size crossover or a Model 3 Performance: $5.50.
• 43 kWh/100 mi, a heavier vehicle: $7.89.

The state matters as much as the car. At 30 kWh/100 mi, California's 34.74 cents makes 100 miles cost $10.42, while Florida's 15.10 cents brings it down to $4.53.

The trip computer is a different number. It measures energy leaving the battery, so it leaves charging losses out. ADAC found it typically reads 10% to 25% lower than what the wall supplied. If that's the only figure you have, add that margin before you multiply by your rate.

Which price per kWh to enter

Use the unit rate from your bill, not the total bill divided by the kWh. If you're on a time-of-use plan, use the rate for the hours you actually charge. Charging overnight on a cheap rate can change the result more than any other input.

Public charging is a different calculation. Many networks charge per kWh, so the same formula works with the station price. Some bill per minute or per session, or add idle fees, and this kind of calculation doesn't cover those.

Rates also date quickly. The Department of Energy's 54 kWh example used 10.7 cents and its per-mile example came out at about 3 cents a mile. The kWh figures in those examples still hold, but the price has moved. Keep the kWh number and reprice it when your rate changes.

What to calculate next

The EV charging cost calculator below takes the same inputs as this guide. Enter your usable battery capacity, the charge level now and the level you're charging to, your rate per kWh and an efficiency that fits how you charge. That's about 90% for a wallbox and lower for a household outlet. It returns the cost of the session and splits the energy into what reached the battery, what came from the grid and what was lost.

Add your car's rated EPA consumption to get the cost per 100 miles, or switch to kilometers and use the WLTP figure. If you're comparing an EV with a gasoline car, the fuel cost calculator works out the same drive on gas. Enter 100 miles as the distance and it gives the trip cost and the cost per mile, so you can put the two side by side.