Reactive power (kVAR) is the non-productive power in AC circuits needed for magnetic fields in motors and transformers.
kVAR = √(kVA² − kW²). From the Pythagorean power triangle.
kVA² = kW² + kVAR². Reactive power is the missing side.
Capacitor bank sizing, PF correction analysis, utility billing.
kW must always be ≤ kVA. If kW = kVA, then kVAR = 0 (unity PF).
Power triangle calculation.
This is the Pythagorean theorem applied to the power triangle. kVA is the hypotenuse.
3 steps using the power triangle.
Read apparent power from your power meter.
Read real power from the same meter.
kVAR = √(kVA² − kW²). Square both, subtract, take square root.
kVAR values for common kVA/kW combinations.
| kVA | kW | kVAR | PF |
|---|---|---|---|
| 100 | 80 | 60.0 | 0.80 |
| 100 | 85 | 52.7 | 0.85 |
| 100 | 90 | 43.6 | 0.90 |
| 100 | 95 | 31.2 | 0.95 |
| 500 | 400 | 300.0 | 0.80 |
| 500 | 425 | 263.4 | 0.85 |
Real-world reactive power scenarios.
500 kVA apparent, 400 kW real:
√(500² − 400²) = 300 kVAR
200 kVA apparent, 170 kW real:
√(200² − 170²) = 105.4 kVAR
100 kVA, 100 kW:
√(100² − 100²) = 0 kVAR (perfect PF)
25 free conversion tools — each with its own unique calculator, interactive visuals, and detailed explanations.
Converter for kva-to-watts
Converter for kva-to-mw
Converter for kva-to-amps
Converter for kva-to-kwh
Converter for kva-to-hp
Converter for kva-to-va
Converter for kva-to-btu
Converter for kva-to-gw
Converter for kva-to-kw-3-phase
Converter for kva-to-joule
Converter for kva-to-kv
Converter for kva-to-ka
Converter for kva-to-mbh
Converter for kva-to-mwh
Converter for kva-to-mva
Converter for kva-to-rpm
Converter for va-to-v
Converter for kw-to-kwh
Converter for power-factor-calculator
Converter for transformer-kva-calculator
Converter for generator-size-calculator
Converter for kva-to-kvar
Converter for kvar-calculator
Converter for watts-to-kwh
Converter for voltage-drop-calculator
Common questions about reactive power calculation.
High kVAR means low power factor, wasted capacity, higher currents, and utility penalties.
Install capacitor banks or synchronous condensers to supply reactive power locally.
No. kVA is always ≥ kW. If your measurements show otherwise, recheck the meters.
A right triangle where kVA is hypotenuse, kW is base (real), and kVAR is height (reactive).
Calculate current kVAR and target kVAR (at desired PF). The difference is the capacitor size needed.