Convert apparent power (kVA) to real power (kW) or the other way round using the power factor — the same conversion used to size generators, transformers, and UPS units.
Choose the conversion direction and enter your known value and power factor.
Converted using your power factor
Converting between apparent power (kVA) and real power (kW) is one of the most common calculations in electrical load planning, generator sizing, and transformer selection. Apparent power represents the total power flowing through a circuit, while real power represents only the portion actually doing useful work. The gap between the two is caused by reactive power drawn by inductive or capacitive loads such as motors, transformers, and fluorescent ballasts.
The power factor (PF) is the ratio that bridges these two quantities, defined as PF = kW ÷ kVA, and always falls between 0 and 1 for a given load. Rearranged, this gives the two directions of conversion this calculator performs: kW = kVA × PF, and kVA = kW ÷ PF. A power factor close to 1 means most of the apparent power is being converted into useful real power, while a low power factor means a larger share of the supply current is reactive and not doing useful work, even though it still has to be supplied and accounted for when sizing equipment.
This tool is especially useful when a nameplate gives one quantity but a design calculation needs the other — for example, converting a generator's kVA rating into the kW load it can actually support, or converting a known real power demand into the kVA capacity required from a transformer or UPS.
Worked example: Suppose a generator is rated at 125 kVA with a power factor of 0.8. The real power it can deliver is kW = 125 × 0.8 = 100 kW. Conversely, if a facility's measured real power demand is 100 kW at the same 0.8 power factor, the equivalent apparent power demand is kVA = 100 ÷ 0.8 = 125 kVA — the figure used to confirm the generator or transformer has enough capacity to serve that load.
As with any sizing calculation, always cross-check the power factor against the actual nameplate or measured value for your load rather than assuming a generic 0.8, since a wrong PF can lead to an undersized or oversized selection.
kVA (kilovolt-amps) is apparent power — the total power supplied to a circuit. kW (kilowatts) is real power — the portion of that supply actually converted into useful work such as heat, light, or motion. The difference between them is reactive power, which is needed by inductive loads but does no useful work itself.
0.8 lagging is a widely used industry default for mixed industrial loads and diesel generators when the exact figure isn't available. However, always check the equipment nameplate first — resistive loads like heaters run near 1.0 PF, while motor-heavy loads can run as low as 0.6–0.7 without power factor correction.
A generator's alternator windings are current-limited, so its fundamental rating is in kVA. The kW it can actually deliver depends on the connected load's power factor, which is why manufacturers publish both figures — typically kVA at 0.8 PF as the reference kW rating.
Yes. Installing APFC (Automatic Power Factor Correction) capacitor banks raises the power factor closer to 1, which reduces the kVA drawn for the same kW load, lowers electricity bills where utilities penalize low PF, and frees up transformer and cable capacity. Use the APFC Capacitor Calculator to size a correction bank for your load.