Electric car charging cost calculator
Charging losses are real: about 10% of what the meter records never reaches the battery. This counts it.
kWh
%
%
per kWh
%
kWh per 100 km
Cost of this charge
11.95
- Energy into the battery
- 38.40 kWh
- Energy off the meter
- 42.67 kWh
- Range added
- 240
- Cost per 100 km
- 4.978
- Cost per kilometre
- 0.0498
- Cost of a full charge
- 19.91
- Saving against petrol per 100 km
- 7.42
Show the working
- Battery capacity = 64
- Starting charge = 20
- Target charge = 80
- Electricity price = 0.28
- Charging losses = 10
- Vehicle efficiency = 16
- Petrol equivalent per 100 km = 12.4
- Energy into the battery = 64 * max(80 - 20, 0) / 100 = 38.4
- Energy off the meter = 38.4 / (1 - 10/100) = 42.6667
- Cost of this charge = 42.6667 * 0.28 = 11.9467
- Range added = 16 > 0 ? 38.4 / 16 * 100 : 0 = 240
- Cost per 100 km = 16 * 0.28 / (1 - 10/100) = 4.977 78
- Cost of a full charge = 64 / (1 - 10/100) * 0.28 = 19.9111
- Saving against petrol per 100 km = 12.4 - 4.977 78 = 7.422 22
- Cost per kilometre = 4.977 78 / 100 = 0.049 777 8
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- energy delivered = battery x (target - start)
- metered energy = delivered / (1 - losses)
Losses are around 10% on AC home charging and 5 to 8% on DC rapid charging, plus battery preconditioning in cold weather.
Charging past 80% is slow on a rapid charger and hard on the battery, which is why the default stops there.