Awaiting Calculation
Enter your values and submit the form to display conversion results here.
Plotly Graph
The chart compares benchmark kVAR values and highlights the active calculation when available.
Formula Used
Reactive power links real power and apparent power through the power triangle. For lagging loads, kVAR is positive. For leading loads, the calculator shows the same magnitude with a negative sign.
Direct conversion
φ = cos-1(PF)
kVAR = kW × tan(φ)
Power factor correction
Existing kVAR = kW × tan(cos-1(PFcurrent))
Required correction = kW × [tan(cos-1(PFcurrent)) − tan(cos-1(PFtarget))]
From kW and kVA
PF = kW ÷ kVA
kVAR = √(kVA² − kW²)
How to Use This Calculator
- Choose the calculation mode that matches your data source.
- Enter the real power value in kilowatts.
- For direct mode, provide the load type and power factor.
- For correction mode, enter both current and target power factor values.
- For the kVA mode, enter the apparent power and optional load type.
- Add operating hours if you want estimated kVARh output.
- Press Submit to show the result above the form and under the page header.
- Use the CSV and PDF buttons to save the result for reporting or design review.
Example Data Table
These sample values help verify expected outputs for conversion and capacitor sizing scenarios.
| Mode | kW | Current PF | Target PF | kVA | kVAR | Note |
|---|---|---|---|---|---|---|
| Direct | 50 | 0.80 | — | 62.50 | 37.50 | Lagging load |
| Direct | 75 | 0.90 | — | 83.33 | 36.32 | Motor feeder |
| Correction | 100 | 0.78 | 0.95 | — | 48.44 | Capacitor requirement |
| From kW & kVA | 60 | 0.75 | — | 80.00 | 52.92 | Power triangle |
| Correction | 150 | 0.82 | 0.97 | — | 56.84 | Plant improvement |
Load Behavior and Phase Angle
Reactive power rises as power factor falls because the phase angle between voltage and current widens. At 50 kW and 0.80 power factor, the calculator returns 37.50 kVAR and 62.50 kVA. At 0.95 power factor, the same 50 kW load needs 16.43 kVAR. This change shows why low power factor increases nonproductive current on cables, breakers, and transformers.
Impact of Power Factor on kVAR
For a 75 kW motor feeder at 0.90 power factor, reactive power is 36.32 kVAR. If the feeder slips to 0.75, reactive demand increases to roughly 66.14 kVAR. That difference is 29.82 kVAR without any increase in useful output. The calculator helps compare these conditions before bills, voltage drop, and thermal loading become operational concerns.
Correction Sizing and Capacitor Planning
Correction mode estimates how much capacitor support is required to move from one operating condition to another. A 100 kW system improving from 0.78 to 0.95 needs about 48.44 kVAR of correction. A 150 kW load improving from 0.82 to 0.97 needs about 56.84 kVAR. These figures are useful for capacitor bank selection and staged compensation reviews.
Apparent Power and Feeder Loading
The power triangle links kW, kVAR, and kVA. When 60 kW is supplied at 80 kVA, the calculator derives 52.92 kVAR and a 0.75 power factor. Although real output stays at 60 kW, the source still carries 80 kVA. Reducing reactive demand lowers apparent power, often improving feeder margin, transformer headroom, and generator utilization at the same duty.
Operating Hours and Reactive Energy
Hours matter when teams convert instantaneous kVAR into monthly or shift-based reactive energy. If a load draws 37.50 kVAR for 160 hours, the result is 6000 kVARh. If correction removes 48.44 kVAR for the same period, avoided reactive energy reaches 7750.40 kVARh. This supports maintenance planning, tariff analysis, and capacitor switching schedules based on actual operating profiles.
Using Results for Design Checks
Use the calculator as a screening tool, then confirm results with metered data, harmonic review, voltage level, and switching duty. It works well for motor groups, plant feeders, HVAC distribution, and generator studies. Final capacitor selection should still consider resonance, step size, temperature, and utility rules so calculated kVAR improves performance without introducing instability.
FAQs
1. What does this calculator convert?
It converts real power into reactive power, estimates capacitor correction demand, and derives kVAR from known kW and kVA values for practical electrical review.
2. Why does lower power factor increase kVAR?
A lower power factor means a larger phase angle. As that angle increases, tangent rises, so reactive power grows even when real power remains unchanged.
3. When should I use correction mode?
Use correction mode when you know the present and desired power factor values and want a first-pass estimate of capacitor kVAR needed for improvement.
4. What is the difference between kW, kVAR, and kVA?
kW is useful power, kVAR is reactive power, and kVA is total apparent power. Together they form the electrical power triangle.
5. Can I use this for capacitor bank sizing?
Yes, it is suitable for preliminary sizing. Final selection should still consider harmonics, switching steps, voltage level, utility limits, and resonance risk.
6. What does reactive energy in kVARh mean?
kVARh estimates reactive demand over time. It helps compare operating periods, tariff exposure, and correction benefits across shifts, days, or monthly duty cycles.