kVA vs kW: What's the Difference and Why It Matters for Generators
Confused by kVA and kW on generator spec sheets? This guide explains the real difference between apparent and real power, the role of power factor, and how to convert kVA to kW.
Rishabh Power Solutions Engineering Team
1 min read
Quick Answer
kVA measures apparent power (total). kW measures real power (usable). The formula: kW = kVA × Power Factor. At PF 0.8, a 100 kVA generator delivers 80 kW.
What Is kVA?
kVA (kilovolt-ampere) = total power flowing in the circuit, including reactive power for magnetic fields in motors and transformers. Generators are rated in kVA because they must handle total current regardless of power factor.
What Is kW?
kW (kilowatt) = only the power that does useful work. Your electricity bill is in kWh because you pay for real power consumed.
Conversion Table (PF 0.8)
| kVA | kW | Application |
|---|---|---|
| 5 | 4 | Small shop |
| 15 | 12 | Small office |
| 25 | 20 | Restaurant |
| 62.5 | 50 | Medium office |
| 100 | 80 | Hospital wing |
| 125 | 100 | Hotel |
| 200 | 160 | Factory |
| 500 | 400 | Industrial plant |
| 1000 | 800 | Major infrastructure |
| 1500 | 1200 | Power plant |
Why Generators Use kVA Not kW
- The alternator doesn't know your power factor — it produces kVA regardless
- Winding heating depends on total current (amps), proportional to kVA
- International standards (ISO 8528, IS 4889) specify kVA ratings
Power Factor by Load Type
| Load | Power Factor |
|---|---|
| LED lighting | 0.90–0.95 |
| Computers | 0.85–0.95 |
| Air conditioners | 0.80–0.90 |
| Industrial motors (running) | 0.75–0.85 |
| Motors (starting) | 0.35–0.50 |
| Welding machines | 0.50–0.60 |
Frequently Asked Questions
Can I use a 100 kVA generator for a 100 kW load?
No. 100 kVA × 0.8 = 80 kW. You need at least 125 kVA (125 × 0.8 = 100 kW). Add 10–20% margin → 140–160 kVA.
Does higher power factor mean smaller generator?
Yes. Improving from PF 0.7 to 0.9 reduces required generator size by ~22%. Power factor correction capacitors pay for themselves in 1–2 years.
Is kVA equal to kW for heaters?
Yes, for purely resistive loads (PF = 1.0). But real-world loads are always mixed, so PF is always below 1.0.
Next Steps
Use our free kVA Calculator | Request a quote | Browse generators (3.5–1500 kVA)
Rishabh Power Solutions Engineering Team
Power engineering insights from Rishabh Power Solutions