So, generating 1 kW of power at 120 volts will draw 8. Equipment is often not 100% efficient with power usage, and this must be factored in to find the number of amps consumed for a given output power. For that just fill the kW and Voltage value in the below two boxes and by pressing the calculating button to get the answer in Amps. The formula is Amps = (kW x 1000) / Volts. For single-phase AC:. This tool will help you convert kilowatts to amperes in a 3-phase electrical system easily. To calculate the current (amps) in a 3-phase system based on the power (in kW), voltage, power factor, and efficiency, follow these steps: Enter the power in kilowatts (kW).