Charging power calculator: amps to kW
Enter the current, number of phases and voltage of a socket or wallbox to get the AC charging power in kilowatts. Add your car's onboard charger limit and the calculator shows the power you will actually get and how many kilometres it adds per hour.
Your car's onboard charger is the limit here, not the socket. A higher current would not charge faster.
Standard European currents and their power
Power at 230 V per phase. Compliant equipment should limit current to the lowest communicated limit, but installation and cable suitability still need to be confirmed.
| Current | Single-phase | Three-phase |
|---|---|---|
| 10 A | 2.3 kW | 6.9 kW |
| 16 A | 3.7 kW | 11 kW |
| 32 A | 7.4 kW | 22.1 kW |
How this is calculated
Single-phase power = voltage × current. At 230 V, 16 A gives 230 × 16 = 3,680 W, about 3.7 kW.
Three-phase power = 3 × voltage × current. At 230 V, 16 A on three phases gives 3 × 230 × 16 = 11,040 W, about 11 kW.
The power you get is the smaller of the socket's power and your car's onboard charger limit. An 11 kW socket charges a 7.4 kW car at 7.4 kW.
Range added per hour = power × efficiency ÷ consumption × 100. At 11 kW and 18 kWh per 100 km, that is about 55 km for every hour of charging.
Assumptions and limits
- AC charging. DC fast charging is rated directly in kW and follows a charging curve this tool does not model.
- European nominal voltage of 230 V per phase; change it if your supply differs.
- The cable and the car also cap the current: a 16 A cable limits a 22 kW station to 11 kW, and the onboard charger caps it further.
- Local connection rules or the building's load limit may cap single-phase charging. Confirm the permitted current for the actual installation.
Frequently asked questions
How do I convert amps to kW for EV charging?
Multiply voltage by current for single-phase (230 V × 16 A = 3.7 kW), or by three for three-phase (3 × 230 V × 16 A = 11 kW). The calculator does this and then caps the result by your car's onboard charger.
How many kW is a 16 A charger?
About 3.7 kW single-phase or 11 kW three-phase at 230 V per phase. The same current gives three times the power on three phases because you are using three live conductors instead of one.
Why does my car charge at less power than the socket provides?
The car's onboard charger sets the AC ceiling, and its power and phase support are vehicle-specific. A socket or wallbox cannot make the car accept more than that limit.
What power do I get from a normal household socket?
At 230 V, the calculator's 10 A single-phase example is about 2.3 kW. This is a power calculation, not approval to charge: the permitted continuous current must be confirmed for the socket, circuit and equipment.
