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EV charging cost calculator

Enter your battery size and state of charge (or the kWh added), plus your electricity rate at home and at the charging station. You get the cost per charge, the energy drawn from the grid including charging losses, your savings from charging at home and the cost per 100 miles.

kWh
%
%
%
Share of grid electricity that never reaches the battery. The US DOE puts charging efficiency at often 84–93% (7–16% loss).
per kWh
Example value – enter the rate from your utility bill
per kWh
Example value – enter the price shown at the charger or in your app
kWh/100 mi
Example value; trip computer figure. 0 = skip per-distance results

Result

Cost of this charge at home
US$6.00
Cost of this charge at a public charger
US$18.00
You save by charging at home
US$12.00
Savings in percent (vs. public charging)
66.67%
Energy into the battery (kWh)
36
Energy from the grid incl. losses (kWh)
40
of which charging losses (kWh)
4
Home charging cost per distance
US$5.00 per 100 mi
Public charging cost per distance
US$15.00 per 100 mi
Range added
120 mi

How it is calculated

How the EV charging cost calculator works

First the calculator works out how much energy goes into the battery. Either you enter the kWh directly (from your car’s app), or it uses battery capacity and state of charge (SoC):

Energy into battery = capacity × (target SoC − starting SoC) ÷ 100

Some electricity is lost while charging – mostly in the onboard charger that converts AC to DC, plus systems running in the car, the cable and the battery itself. You pay for what comes out of the grid, though. The calculator defines charging loss as the share of grid energy that does not reach the battery (the same definition as the ADAC measurements and 1 − charging efficiency in the DOE figures):

Energy from grid = energy into battery ÷ (1 − loss)
Cost = energy from grid × price per kWh

Multiplying by (1 + loss) instead understates the grid energy slightly: 36 kWh at 10% loss is 40.00 kWh from the grid, not 39.60 kWh.

Worked example with the default values

60 kWh battery charged from 20% to 80%, 10% charging loss, example prices of $0.15/kWh at home and $0.45/kWh at a public charger:

The prices are neutral example values, not national averages – enter the rate from your own bill and your charging network’s price. Membership or session fees and idle fees are not included.

How big are charging losses?

The US Department of Energy states on fueleconomy.gov that battery charging efficiency “can vary, but it is often 84% to 93%” – a loss of 7–16%. Measurements by the German automobile club ADAC on five current models found 5.1–7.0% loss on an 11/22 kW wallbox (Level 2), 12.7–24.2% on a household socket and 5–15% in total for DC fast charging, depending on how much energy went into warming the battery.

The default of 10% sits inside the DOE range. For Level 2 charging you might enter about 7%, for a standard household outlet about 15% – in the example that raises grid energy to 36 ÷ 0.85 = 42.35 kWh. According to ADAC, the car’s trip computer does not show these losses.

Miles per kWh, cost per 100 miles and range

Enter your efficiency in kWh/100 mi or mi/kWh (100 ÷ mi/kWh = kWh/100 mi, e.g. 3.5 mi/kWh = 28.57 kWh/100 mi), or switch to kWh/100 km. The calculator returns the cost per 100 miles including losses (kWh/100 mi ÷ (1 − loss) × price) and the range added (energy into battery ÷ kWh/100 mi × 100). At 3.5 mi/kWh, the 36 kWh give 126 miles at $4.76 per 100 miles when charging at home. Real-world range varies with speed, temperature and climate control, so treat it as an estimate.

Frequently asked questions

How do I calculate the cost to charge my EV?

Divide the kWh added to the battery by (1 − charging loss) and multiply by your price per kWh. Example: 36 kWh at 10% loss is 40 kWh from the grid – $6.00 at $0.15/kWh.

How much does it cost to charge 50 kWh?

With 10% loss, 50 ÷ 0.9 = 55.56 kWh come from the grid. At $0.40/kWh that is $22.22; without losses it would be $20.00.

How much energy is lost when charging an EV?

The US DOE puts charging efficiency at often 84–93%, i.e. 7–16% loss. ADAC measured 5.1–7.0% on a Level 2 wallbox, 12.7–24.2% on a household socket and 5–15% for DC fast charging.

How do I convert mi/kWh to kWh/100 miles?

kWh/100 mi = 100 ÷ mi/kWh. 3.5 mi/kWh equals 28.57 kWh/100 mi, and 4 mi/kWh equals 25 kWh/100 mi. The calculator accepts either unit.

How much do I save by charging at home?

Savings = energy from the grid × (public price − home price). With the example prices of $0.15 and $0.45/kWh, a 40 kWh charge saves $12.00, or two thirds of the public cost.

What does SoC mean?

State of charge – the battery level in percent. Charging a 60 kWh battery from 20% to 80% adds 60 × 0.6 = 36 kWh.

Sources and legal basis

As of:

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