Convert real power (kW) to load current (A) or the other way round, for single-phase or three-phase supply, using voltage and power factor.
Pick single or three phase, choose the conversion direction, then enter your known values.
Converted using voltage & power factor
Converting between load current (A) and real power (kW) is a core calculation whenever a nameplate gives one quantity but a design task — cable sizing, breaker selection, or load scheduling — needs the other. Real power is the portion of the supply actually converted into useful work, and it depends on three things: the supply voltage, the current drawn, and the power factor of the load.
For a single-phase supply, the relationship is kW = (V × I × PF) / 1000, where V is the line voltage, I is the current in amps, and PF is the power factor. Rearranged for the reverse direction: I = (kW × 1000) / (V × PF). For a three-phase supply, the same relationship gains a √3 (≈1.732) term to account for the phase geometry: kW = (√3 × V × I × PF) / 1000, and reversed, I = (kW × 1000) / (√3 × V × PF). This calculator switches between the two automatically based on the supply type you select.
Power factor matters because it separates the useful (real) portion of power from the reactive portion drawn by inductive loads such as motors and transformers. A load with PF 1.0 (purely resistive, like a heater) draws the least current for a given kW; a load with a low PF, such as an uncorrected induction motor, draws more current for the same real power output, which is why undersized cables or breakers can overheat even when the "power rating" looks fine on paper.
Worked example: A 415 V three-phase motor draws 15 A at PF 0.85. Power = (1.732 × 415 × 15 × 0.85) / 1000 ≈ 9.17 kW. Conversely, a 22 kW heater at 230 V single-phase, PF 1.0, draws I = (22 × 1000) / (230 × 1) ≈ 95.65 A.
Always confirm the actual line voltage and power factor for your installation — nominal voltage can vary regionally, and power factor changes with load type and loading percentage — before using the result to size cables, breakers, or protective devices.
In a balanced three-phase system, the line-to-line voltage and line current are offset by 120° across the three phases. The √3 (≈1.732) factor accounts for this vector relationship between line voltage and phase voltage, and appears in every standard three-phase power formula.
This calculator expects line-to-line voltage for three-phase systems (e.g. 415 V) and line-to-neutral voltage for single-phase (e.g. 230 V), which is how supply voltage is normally specified on nameplates and utility connections in most countries.
Yes. Since kW is fixed by the load's actual power demand, a lower PF means the same kW must be delivered through more current, which is why low-PF loads need larger cables and breakers than a PF-1.0 load of the same kW rating.
It gives the correct current or power figure to start from, but final cable and breaker sizing should also account for ambient temperature, installation method, cable length (voltage drop), and a safety margin per local wiring codes — use the Cable Size Calculator as the next step.