Power Calculator: kW and Power Factor
Put in what your meter says. Pick a check below.
Power factor (PF or λ on the clamp) is optional.
Inverter load: part of the gap between volts × amps and true kW is harmonic distortion, not reactive power, so the triangle would lie. The kW is still good.
More detail
A drive takes current in pulses near the peaks, not a sine wave — so its power factor can't be turned back into an angle.
Advanced
Power factor, kW and amps.
Type any two. The third fills in.
Volts times amps. On a motor or an inverter the true watts are lower; power factor is under Advanced.
Know any two? The rest fill in.
Amps need volts to become a power figure.
Fixed-speed maths; illustration only on an inverter. Running figures — not maximums, nothing to size protection from.
Any two in, the other two out. The element check in one line: 230 V across the measured ohms should land on the rated watts.
Resistive loads only: elements, immersions, crankcase and trace heaters.
Clamp L and N together (all lives and N on three phase) — whatever shows is going to earth.
A device may operate anywhere above half its rating. A ramp-test figure replaces the window with this device's own number.
Megger each live to earth — the MΩ becomes the current that path can pass.
Isolate and disconnect the drive/PCB before a 500 V test. Your manual's minimum wins.
£2.80at 1.34 kW for 8.0 h
26.11 p/kWh is the Ofgem capped unit rate for Jul–Sep 2026. Change it to the customer's actual rate before you quote a figure.
Running draw only. Not for sizing cables, protective devices or supplies.
More electrical checks: Ohm's law calculator →