Estimate what it costs to charge an electric car at home. Enter the battery size, the start and target state of charge, your $/kWh rate, the charger power and a charging efficiency — the tool returns the energy added to the battery, the energy drawn from the wall, the dollar cost and the charge time. The preset (a 60 kWh pack from 20% to 80% at $0.15/kWh on a 7.2 kW charger) adds 36 kWh, pulls 40 kWh from the wall, costs $6.00 and takes about 5 hours.
Results are estimates for planning and education, based on your inputs and standard engineering values (AWG resistance, NEC ampacity, resistivity). Electrical work can be dangerous and is governed by the NEC and your local code — verify all sizing with a licensed electrician and your authority having jurisdiction (AHJ). Not a substitute for professional design.
Calculator
Energy added to battery
36.0 kWh
Energy drawn from wall
40.0 kWh
Cost to charge
6.00 $
Charge time
5.0 h
Formula
Energy into the battery = battery capacity × (target% − start%) ÷ 100. Energy drawn from the wall = battery energy ÷ efficiency, because some power is lost as heat in the charger and cabling. Cost = wall energy × your rate ($/kWh). Charge time in hours = battery energy ÷ charger power (kW). The rate is yours to enter — no tariff is stored — so the cost stays accurate wherever and whenever you charge.
Worked example
Charge a 60 kWh EV from 20% to 80%. Energy into the battery = 60 × (80 − 20) ÷ 100 = 36 kWh. At 90% charging efficiency the wall draws 36 ÷ 0.9 = 40 kWh. At $0.15 per kWh that is 40 × 0.15 = $6.00. On a 7.2 kW Level 2 charger the time is 36 ÷ 7.2 = 5 hours. A slower 3.6 kW unit would take about 10 hours for the same charge.
Frequently asked questions
How much does it cost to charge an EV at home?
Multiply the energy you add by your electricity rate, then divide by charging efficiency to account for losses. Adding 36 kWh to a battery at 90% efficiency draws 40 kWh from the wall; at $0.15 per kWh that costs $6.00. A full charge of a typical 60 kWh pack from near-empty costs roughly $8 to $12 at average US rates. Home charging is usually far cheaper per mile than public fast charging or gasoline.
Why is the energy from the wall higher than the energy added to the battery?
Charging is not perfectly efficient. Some energy is lost as heat in the onboard charger, the cabling and the battery itself, and a little runs the car’s thermal management while charging. Typical AC home-charging efficiency is around 85% to 92%, so the wall draws roughly 8% to 18% more energy than ends up stored. You pay for the wall energy, so the calculator divides the battery energy by efficiency before applying your rate.
How long does it take to charge an EV at home?
Divide the energy you need by the charger power in kilowatts. Adding 36 kWh on a 7.2 kW Level 2 charger takes 36 ÷ 7.2 = 5 hours. A standard 120 V Level 1 outlet delivers only about 1.4 kW, so the same charge would take over a day — Level 1 is best for slow overnight top-ups. Real times run slightly longer near 100% as the car tapers the charge rate to protect the battery.
What charger power should I enter?
Use the actual delivered power. A 120 V Level 1 cord delivers about 1.2 to 1.4 kW. A 240 V Level 2 home charger commonly delivers 7 to 11 kW, limited by the circuit and the car’s onboard charger — enter the lower of the two. The preset 7.2 kW reflects a common 32-amp Level 2 setup. DC fast charging is far higher but is a public-station scenario, not typical home charging.
Should I charge from 0% to 100%?
For everyday use, most manufacturers recommend keeping a lithium-ion EV roughly between 20% and 80% to slow battery aging, charging to 100% only before a long trip. That is why the calculator works from a start percent to a target percent rather than assuming a full charge. Charging the 20–80% window also avoids the slow taper near full, so it is both gentler on the pack and quicker per kWh added.
How do I compare charging cost to gasoline?
Work out cost per mile for each. If charging 36 kWh adds about 130 miles, $6.00 is roughly 4.6 cents per mile. A 30 mpg car at $3.50 a gallon is about 11.7 cents per mile. EV home charging is usually cheaper, though the gap depends heavily on your electricity rate and local fuel price — which is exactly why this tool asks you to enter your own rate instead of assuming one.
Source: Battery energy × (target − start); wall = energy ÷ efficiency; cost = wall × the user-entered $/kWh rate (no tariff hardcoded). · All sources