About the kW to Amps Calculator
Equipment such as electric showers, ovens, EV chargers and generators is rated in kilowatts, but cables, breakers and isolators are chosen by current in amps. This calculator converts kilowatts to amps by dividing the power in watts by the voltage, and by the power factor for AC. For three-phase supplies it also divides by the square root of three. The result tells you the current each conductor must carry, which is the starting point for choosing protective devices and cable sizes.
Updated October 2026
How to use the kW to Amps Calculator
- 1Choose DC, single-phase or three-phase.
- 2Enter the power in kilowatts.
- 3Enter the supply voltage, line to line for three-phase.
- 4Enter the power factor for AC loads.
- 5Read the current in amps.
Examples at a glance
A 3 kW electric heater on 230 volts needs 13 amps, just inside a 13 amp plug. A 22 kW three-phase EV charger at 400 volts draws 31.8 amps per phase when the power factor is 1. A 100 kW generator at 415 volts, power factor 0.8, supplies about 174 amps per phase.
Use the nameplate current on equipment where it is available, as it includes the real efficiency and power factor.
As a rule of thumb for single-phase 230 volt supplies, each kilowatt is about 4.3 amps, and on three-phase 400 volt supplies each kilowatt is about 1.4 amps. These quick numbers help you scan a list of appliances before you do the exact calculation. If the total looks close to the limit of your supply, run the exact figures here and consider spreading the loads across phases or staggering the times when large appliances are switched on.
What affects the answer
- Voltage: higher voltage means lower current.
- Number of phases: three-phase halves the current of single-phase for the same power roughly.
- Power factor: lower values raise the current.
- Efficiency: motors draw more power from the supply than they deliver.
- Starting current: motors can draw 5 to 7 times the running current for a moment.
Related tools
Use the Amps to kW Calculator for the reverse sum, the Wire Gauge Calculator for cable sizes, the Voltage Drop Calculator for long runs and the kVA to kW Calculator for generator ratings. The Power Converter changes between kilowatts, horsepower and other power units.
Features
- Kilowatts to amps in one step
- DC, single-phase and three-phase
- Power factor included
- Works for generators, ovens and EV chargers
- Plain error messages
- Free and private
Frequently asked questions
How do I convert kW to amps?
Multiply kilowatts by 1,000 to get watts, then divide by the voltage and the power factor. For three-phase, also divide by 1.732. An 11 kW three-phase load at 400 volts and a power factor of 0.9 draws about 17.6 amps per phase.
How many amps is 10 kW?
At 230 volts single-phase and a power factor of 1, it is about 43.5 amps. At 400 volts three-phase and a power factor of 1, it is about 14.4 amps. Higher voltage and more phases cut the current.
How many amps does a 7 kW EV charger use?
A 7 kW charger on a 230 volt single-phase supply draws about 30 amps. Most home chargers are set to 32 amps, which gives about 7.4 kW.
Does the power factor change the answer much?
Yes. The same 10 kW load at a power factor of 0.8 draws 25 percent more current than at 1.0. If you don't know the power factor, using 0.8 for motor loads gives a cautious result.
Should I size my breaker at exactly this current?
No. Breakers and cables normally need extra capacity, and continuous loads are often limited to 80 percent of the rating. Motors need allowance for starting current. Check your national wiring rules or ask an electrician.
Why is three-phase current lower for the same power?
The load is shared across three conductors, and each carries less current. The square root of three in the formula reflects the way the phases combine, which is why industrial supplies use three phases for big machines.