kW vs kVA: What Do They Really Mean?
If you only remember one thing, remember this: kW is real usable power, while kVA is total apparent power.
In simple terms, kW tells you how much work your equipment can actually do, and kVA tells you the generator’s total electrical capacity.
They are connected by power factor:
kW = kVA × Power Factor (PF)
So no, kW and kVA are not the same—and this difference matters when choosing a generator.
What is kW?
kW (kilowatt) is the real power that performs useful work.
This is the power that runs your machines, pumps, tools, lighting, and other loads.
When users ask, “How much load can this generator really run?” they are usually asking about kW.
What is kVA?
kVA (kilovolt-ampere) is apparent power—the total power supplied by the system.
It includes:
- real power (kW), and
- reactive power (the part needed to support magnetic fields in motors, transformers, etc.)
Because of this, kVA is usually higher than kW.
Why do generators often use kVA ratings?
Generator manufacturers often rate sets in kVA because it reflects total capacity under different load types.
But for practical load planning, users must still check kW and power factor.
A common assumption in generator sizing is PF = 0.8.
Example:
- Generator rating: 100 kVA
- Power factor: 0.8
- Real output: 100 × 0.8 = 80 kW
So a 100 kVA generator is typically about 80 kW at PF 0.8.
Common buying mistake
A frequent mistake is choosing only by kVA and ignoring kW and PF.
That can lead to:
- undersized generators (overload risk), or
- oversized generators (higher cost and inefficient operation)
A better approach:
- List all loads
- Separate running power and starting power
- Convert correctly between kW and kVA
- Keep a reasonable safety margin
Final answer
kW = usable output power.
kVA = total apparent power capacity.
Both are essential for correct generator selection, but if you care about real working output, focus on kW—while using kVA + PF to size the system properly.