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EV Charger Cost and Charge Time Calculator

Enter a charger's amps and volts, how many miles or kWh you need, and your electric rate. See charge time, cost per session, cost per mile and the breaker size a 125% continuous-load rule implies.

The charger
V

Level 2 chargers run at 208 to 240 V. 40 A and 48 A models are common; see our charger guide.

kW

Many cars accept less than the charger can give. Find it in your owner's manual or the maker's spec sheet.

How much you need to add
miles
kWh

27 kWh per 100 miles is the example used by the U.S. Department of Energy's Alternative Fuels Data Center. Your car's figure will differ.

%

Some energy is lost as heat. 10% is our assumption, not a measurement.

Your electricity
¢ / kWh

A state fills in its EIA residential average for August 2026. The per-kWh rate on your bill is better. On a time-of-use plan, use the rate for the hours you charge.

¢ / kWh

Enter it to see what shifting charging to off-peak hours would save. See time-of-use rates.

An estimate from the figures entered, not a quote, a design or electrical advice. Defaults verified Oct 24, 2026. How it is calculated.

Level 2 charging depends on three things: the charger’s power, how much energy you need, and what your electricity costs. This tool combines them. It supports our charger guides, including best Level 2 EV chargers for home and hardwired vs plug-in chargers.

How it is calculated

  1. Charger power (kW) = volts × amps ÷ 1,000. Example: 240 × 40 ÷ 1,000 = 9.6 kW.
  2. Effective power = the lower of charger power and your car’s maximum AC rate, if entered.
  3. Energy added (kWh) = miles × (kWh per 100 miles ÷ 100), or the kWh you enter.
  4. Energy from the wall (kWh) = energy added ÷ (1 − losses). Losses are an assumption you can change; the default is 10%.
  5. Charge time (h) = energy from the wall ÷ effective power.
  6. Cost per session = energy from the wall × rate (¢ ÷ 100). Cost per mile = cost ÷ miles.
  7. Breaker = amps × 1.25, then the next standard size up.

Worked example with the defaults (240 V, 40 A, 40 miles a day at 27 kWh per 100 miles, 10% losses, U.S. average 18.16¢):

  • Power: 240 × 40 ÷ 1,000 = 9.6 kW.
  • Energy added: 40 × 0.27 = 10.8 kWh; from the wall: 10.8 ÷ 0.90 = 12.0 kWh.
  • Time: 12.0 ÷ 9.6 = 1.25 hours, or 1 h 15 min.
  • Cost: 12.0 × 0.1816 = $2.18, or $0.054 per mile.
  • Breaker: 40 × 1.25 = 50 A.

Where the defaults come from

  • 27 kWh per 100 miles is the example efficiency in DOE’s Alternative Fuels Data Center, Charging at home. Cars vary widely.
  • Electric rate: the U.S. average is EIA’s residential average price for August 2026 (18.16¢ per kWh, Electric Power Monthly Table 5.6.A, preliminary). Choosing a state fills in that state’s August 2026 EIA average. These are statewide averages across all utilities; your bill’s rate is better. See rates by state.
  • Breaker rule: DOE’s AFDC says the NEC treats EV charging as a continuous load. The 125% figure is the common application of that rule, not a substitute for an electrician’s sizing.
  • 10% losses is our assumption, not a measurement.

Limitations

  • Charge time assumes a constant rate. Cars slow down as the battery fills and in cold weather.
  • Cost uses one flat rate. Time-of-use plans, demand charges and fixed charges are not modeled, except through the optional off-peak comparison.
  • The federal 30C charger credit covered property placed in service through June 30, 2026, per the IRS, so it does not apply to a charger installed now. Installation costs are not included. See rate guides.
  • Not electrical, tax or financial advice. Hire a licensed electrician.

Frequently asked questions

How long does it take to charge an EV on a 40-amp Level 2 charger?

A 40 A charger on 240 V delivers 240 × 40 ÷ 1,000 = 9.6 kW. Adding 40 kWh takes about 40 ÷ 9.6 = 4.2 hours if the car accepts that rate, longer once you include charging losses.

What breaker size does an EV charger need?

DOE's Alternative Fuels Data Center says the National Electrical Code treats EV charging as a continuous load. A common reading is a breaker at 125% of the charger's current: 40 A needs 50 A and 48 A needs 60 A. A licensed electrician confirms wire gauge, breaker and panel capacity for your home.

How much does it cost to charge an EV at home?

Energy used times your electric rate. For example, 12 kWh from the wall at 18.16¢ per kWh is about $2.18. Your rate, your plan's time-of-use hours and the car's efficiency change the result.

Why is my car slower than the charger?

Many cars accept less AC power than a charger can supply. Enter the car's maximum AC charge rate in kW and the tool uses the lower of the two.