kVA, kW & Power Factor Calculator

kW measures real power - the power that actually performs work by turning motors, producing heat, or lighting lamps - and is what shows up on the energy portion of your electricity bill. kVA measures apparent power, the total electrical burden the supply must handle including reactive current that does no net work but still flows through conductors and transformers. The two are equal only when power factor is 1.0 (a purely resistive load). For most industrial facilities with induction motors, PF runs 0.75–0.90, so kVA is noticeably higher than kW and the difference must be accounted for when sizing electrical infrastructure.

Transformers, switchgear, and distribution cables are rated in kVA because their thermal limits depend on total current, not just the real-power portion. A cable carrying 100 A at 0.70 PF is just as thermally stressed as one carrying 100 A at 1.0 PF, even though the low-PF cable delivers less useful work. By billing on kVA demand, utilities recover the cost of the infrastructure required to serve the full current drawn by inductive loads. Many commercial tariffs include a power-factor clause that applies a penalty multiplier to the demand charge when PF falls below a threshold such as 0.90.

The most common method is connecting capacitor banks at or near inductive loads such as motors, transformers, and induction furnaces. Capacitors draw leading reactive current that cancels the lagging reactive current of inductors, reducing the net reactive demand seen by the utility. Automatic power-factor correction (APFC) panels monitor reactive power and switch capacitor stages on and off via contactors to maintain a target PF near 0.95 across varying load conditions throughout the day. For variable-speed drives, active front-end rectifiers can maintain near-unity PF electronically without any external capacitors.

No. Power factor is defined as kW ÷ kVA, and since real power (kW) is always less than or equal to apparent power (kVA), PF is bounded between 0 and 1. A system with oversized capacitors can become leading (capacitive), meaning reactive current flows in the opposite direction from the usual lagging direction - but the PF magnitude is still less than or equal to 1. In practice, leading PF above about 1.02 (measuring displacement PF only) causes overvoltages and can trip generator voltage regulators, so it is just as problematic as low lagging PF and must be avoided.

Reactive power (kVAR) represents energy that sloshes back and forth between the magnetic field of an inductor or the electric field of a capacitor and the power source, completing a full round trip every half cycle of the AC waveform. It does no net work over a full cycle - it neither heats nor illuminates anything - but it does flow as real current through real conductors and transformers, causing I²R losses in wires and loading up transformer cores along the way. The kVAR figure from this calculator tells you directly how large a capacitor bank (in kVAR) would be required to locally supply that reactive demand and reduce the reactive burden at the utility meter to zero.