When you need this conversion
kW to kVA conversion is central to sizing generators, transformers, UPS units, and hybrid solar inverters, all of which are rated in kVA (apparent power) even though the loads they serve are usually described in kW (real power). Undersizing a generator by ignoring this gap is one of the most common mistakes in backup power and off-grid system design.
The formula explained
Apparent power in kVA equals real power in kW divided by the power factor:
kVA = kW ÷ Power Factor
Power factor represents the ratio of real, usable power to total apparent power a circuit demands. A power factor of 1 means kW and kVA are equal; anything below 1, typical of motors, compressors, and mixed household loads, means the equipment must be rated higher in kVA than the kW figure alone would suggest, since it also has to handle the reactive component of current.
Common values at a glance
| Real load (kW) | kVA at PF 0.8 | kVA at PF 0.95 |
|---|---|---|
| 2 kW | 2.5 kVA | 2.11 kVA |
| 5 kW | 6.25 kVA | 5.26 kVA |
| 8 kW | 10.0 kVA | 8.42 kVA |
| 10 kW | 12.5 kVA | 10.53 kVA |
| 20 kW | 25.0 kVA | 21.05 kVA |
Practical tips
- Always size a generator or transformer by kVA, not kW, since the equipment's windings and conductors are rated for total current, which depends on apparent power.
- 0.8 is a reasonable default power factor for a mixed load of motors, pumps, and electronics; resistive loads and modern electronics with active power factor correction often run closer to 0.95 to 1.
- Hybrid and off-grid solar inverters list both a kW (continuous real power) and kVA (apparent power) rating; check both against your expected loads, especially for motor-driven appliances with low power factor.
- Undersizing equipment by using kW where kVA is required is a common cause of nuisance tripping or overheating under mixed inductive loads.