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EV charging cost calculator

A 75 kWh battery charged from 20% to 80% puts 45 kWh into the cells, pulls about 51 kWh off the meter once charging losses are counted, and costs roughly $8.70 at $0.17/kWh — about $0.049 a mile at 3.5 mi/kWh, against $0.107 for a 30 mpg petrol car at $3.20 a gallon. Change any of those below.

Your charge

Home AC charging typically lands at 85–90% efficiency — you pay at the meter, the car counts what reaches the cells. DC fast charging is higher at the plug but billed at a far higher rate.

$8.69

45.0 kWh into the battery, 51.1 kWh off the meter — 6.1 kWh ($1.04) lost to charging losses. That is about 158 miles at $0.055/mile.

Against a petrol car

Electric $0.055/mile · petrol $0.107/mile

Charging costs 48% less per mile, or about $618 a year at 12,000 miles.

The number most calculators leave out

Your car reports the energy that reached the battery. Your utility bills the energy that left the wall. Between them sit the onboard charger, the cabling and the thermal management that heats or cools the pack while it charges — roughly 10–15% on home AC charging. A calculator that multiplies battery size by rate and stops there is not describing your bill; it is describing the car’s dashboard.

Same principle as everything else here: the honest unit is what you actually pay, divided by what you actually get. For the cable that carries it, see the cost per foot of EV extension cords, and for the running-cost article the full breakdown of charging costs.

Frequently asked

How much does it cost to charge an electric car at home?

Multiply the kWh you put in by your electricity rate, then divide by charging efficiency. A 75 kWh battery taken from 20% to 80% puts 45 kWh into the cells, draws about 51 kWh at the meter at 88% efficiency, and costs roughly $8.70 at $0.17/kWh. A full 0–100% charge on the same car is about $14.50.

Why is the electricity I pay for more than the car reports?

Because the meter counts what leaves the wall and the car counts what reaches the cells. AC home charging loses roughly 10–15% to the onboard charger, the cabling and battery conditioning — heating or cooling the pack while it charges. Any calculator that skips this understates the bill by about a tenth.

Is charging an EV cheaper than petrol?

At home, almost always, and the comparison has to be per mile because the two fuels are sold in different units. At $0.17/kWh and 3.5 mi/kWh, electricity runs about $0.049 a mile; a 30 mpg petrol car at $3.20 a gallon runs about $0.107. Public DC fast charging is a different calculation — at peak rates it can match or exceed petrol per mile.

What electricity rate should I use?

The marginal rate on your bill for the hours you actually charge, not the average. On a time-of-use tariff, overnight rates are often less than half the peak rate, and charging is one of the few large loads you can move entirely into the cheap window. Use the delivered rate including per-kWh delivery charges, not just supply.

Does a longer charging cable cost more to run?

Not measurably at household lengths. Voltage drop rises with length, which is why cords are built with heavier conductors at higher amperage ratings, but over 21–40 ft the loss is small next to the 10–15% conversion loss already in the system. Buy the length you need — and note that the longer cord is cheaper per foot.

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