Electric car charging cost calculator
The meter records more energy than reaches the battery, typically 10% more, so cost depends on energy drawn. And fast chargers slow sharply above 80%, which is why a 10–80% stop is quicker than the arithmetic suggests.
- Charging time
- 4 h 52
- Energy added to the battery, kWh
- 36.0
- Energy drawn from the grid, kWh
- 40.0
- Lost to heat, kWh
- 4.0
- Range added, km
- 212
- Cost per 100 km
- $24.56
- Cost of a full charge
- $86.67
The formula
Energy stored = capacity × (end − start). Energy drawn = stored ÷ efficiency. Cost = drawn × tariff. On chargers above 22 kW, the rate above 80% is taken as half the rated power to reflect taper.
Worked example
A 60 kWh battery charged from 20% to 80% on a 7.4 kW home charger at 90% efficiency: 36 kWh stored, 40 kWh drawn, 52 at 1.30 per kWh, about 4 h 52, and around 212 km of range at 17 kWh per 100 km.
How to use it
- 1Use the usable capacity, which is a few kWh below the gross figure in the brochure.
- 2Home charging runs at 85% to 92% efficiency; DC fast charging is usually higher at the charger but costs more per kWh.
- 3Your car’s maximum charging rate caps the speed as well as the charger’s — a 150 kW charger cannot exceed what the car accepts.
Questions people ask
Why does charging slow down near full?
To protect the battery, the charging current is reduced as cells approach full voltage. Above about 80% on a fast charger, the last fifth can take as long as the first four.
How does this compare with petrol or diesel?
Put the same distance and your fuel price into the fuel cost calculator. At home electricity prices an electric car typically costs a third to a half as much per kilometre; on public fast chargers the gap narrows.
Last reviewed: 2026-10-20