kW to kVAR Calculator
Convert kW and power factor to reactive power (kVAR) for motor loads and PF correction. Example: 10 kW @ PF 0.85 ≈ 6.19 kVAR lagging.
Calculator
Quick: kW presets and PF band. Advanced: switch direction to solve kW from a target kVAR.
About this calculator
Estimates lagging reactive power (kVAR) from real power and PF using the power triangle—useful for capacitor bank screening and comparing against utility PF penalties. Part of the Power Calculator hub (featured topic).
Calculation Results
Engineering disclaimer
Estimate only—harmonics, leading PF, and unbalance need site measurements. Final capacitor bank design requires engineering review.
kW to kVAR chart (PF 0.85, lagging)
kVAR = kW × tan(arccos PF) at PF 0.85. Open a row to load the calculator.
Formula & Explanation
For lagging loads: kVA = kW ÷ PF and kVAR = √(kVA² − kW²), equivalent to kVAR = kW × tan(arccos PF).
Example: 10 kW @ PF 0.85 → kVA = 11.76, kVAR = √(11.76² − 10²) ≈ 6.19 kVAR. At PF 0.80, the same 10 kW needs 7.50 kVAR—lower PF means more reactive power for the same real work.
See also kW to kVA, 3-phase power, and the power factor formula.
Learn About Power Factor
Understand power factor formulas, typical industrial values, correction methods, and utility penalty rules in our central topic guide.
Typical motor reactive power (PF 0.85)
| Load | kW | kVAR |
|---|---|---|
| Small motor | 7.5 | 4.64 |
| Medium motor | 30 | 18.57 |
| Plant block | 200 | 123.78 |
Frequently Asked Questions
How do I calculate capacitor bank size for power factor correction?
Find required kVAR with kVAR = √(kVA² − kW²) where kVA = kW ÷ PF. Example: 100 kW @ 0.85 PF needs ~62 kVAR correction to reach unity. Use this calculator, then see capacitor bank sizing guide.
What is PF penalty in an electricity bill?
Utilities charge when power factor falls below a threshold (often ~0.90–0.95). Low PF raises apparent power (kVA) and reactive demand. Estimate kVAR here, then read PF penalty rules & cost impact.
How do I convert kW to kVAR?
Find kVA = kW ÷ PF, then kVAR = √(kVA² − kW²). Example: 10 kW @ 0.85 PF → 6.19 kVAR. Use the calculator.
Is kVAR equal to kW?
No. kW is real power; kVAR is reactive. They match only at PF 1.0 when kVAR = 0.
What does a PF of 80% mean?
PF 0.80 means 80% of apparent power is real; the rest is reactive. 10 kW @ 0.80 PF → kVA 12.5, kVAR ≈ 7.5. Compare with 10 kW @ 0.80 PF preset.
What is kVAR vs kW?
kW does useful work; kVAR supports magnetic fields in motors and transformers. Utilities and capacitors care about kVAR for PF correction.
How much kVAR for 50 kW at 0.85 PF?
About 30.95 kVAR lagging (kVA ≈ 58.82). Open 50 kW preset.