DinSketchThe current relationships
For single-phase active power, I = P / (U × power factor). For a balanced three-phase load, I = P / (√3 × U × power factor), where U is line-to-line voltage. Use the input units shown by the calculator.
What changes the current
For the same active power, a lower voltage or power factor increases calculated current. With a motor, distinguish mechanical output power from electrical input power; efficiency belongs to the appropriate motor calculation.
Use the result as an input
Operating current is not an automatic recommendation for a breaker rating. Check cable ampacity, load behavior, starting current and protective-device characteristics next. Avoid selecting protection from one number alone.
Questions and answers
How many watts are in one kilowatt?
1 kW equals 1000 W. Check the calculator input unit before entering a value.
Which voltage applies to three-phase loads?
The balanced three-phase model uses voltage measured between phases.