Use this calculator to estimate how long a home charge will take and what it will cost. Enter your battery size, the charging power available at your property and your electricity rate, and it will work out charging time, energy used and cost.
It is most useful for comparing a standard rate against an off-peak or EV tariff, and for checking whether a faster charger would actually help on your electricity supply.
How to read the results
The figures are an estimate, not a guarantee. Real charging sessions differ because:
- Charging slows as the battery approaches full, so the last part of a session takes longer than the average rate suggests.
- Some energy is lost as heat during charging, so the electricity drawn from the meter is higher than the energy stored in the battery.
- Cold weather increases losses and can reduce the rate the car accepts.
- Your car’s onboard charger, not the wall unit, sets the maximum AC charging speed.
- Load balancing may reduce charger output when the rest of the home is drawing power.
Treat the result as a planning figure for comparing tariffs and charger speeds rather than an exact prediction of a single session.
Understand the numbers behind the calculator
- EV Onboard Chargers Explained — why your car, not the charger, often sets the speed
- 7kW vs 22kW EV Chargers — whether a faster unit will actually charge faster at your home
- Smart Tariffs and EV Charging — how off-peak and intelligent tariffs change the cost
- Charging an EV from Solar Panels — using solar surplus instead of grid electricity
- Dynamic Load Balancing Explained — why charger output can drop mid-session
Planning a home charger installation?
Charging speed depends on your electricity supply, your car and the installation as much as the charger you buy.