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Power Factor Correction Calculator
Calculate the capacitor bank size in kVAR needed to correct a lagging power factor to a target value, plus the resulting kVA demand and line current reduction.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Capacitor Rating Needed (Qc)
Apparent Power Reduction
Line Current Reduction
Power Triangle & Loading Comparison
| Electrical Parameter | Before Correction (PF 0.75) | After Correction (PF 0.95) |
|---|
How it works
- Enter your facility active electrical load in kilowatts (kW) or horsepower (HP).
- Specify operating voltage and system phase (3-phase or single-phase).
- Input your existing lagging power factor (e.g. 0.75) and your desired target power factor (e.g. 0.95).
- The calculator determines the exact capacitor bank size in kVAR and calculates kVA demand and line amp reductions.
The formula
Required Capacitor Rating Qc (kVAR) = P (kW) × [tan(arccos(PF₁)) − tan(arccos(PF₂))]
Apparent Power S (kVA) = P (kW) / Power Factor
FAQ
What is Power Factor and why should it be corrected?
Power factor (PF) is the ratio of real working power (kW) to apparent power (kVA) drawn from the electrical grid. A low lagging power factor (caused by inductive loads like electric motors and transformers) causes excessive current draw, higher cable I²R heat losses, and utility low-PF penalty surcharges.
How do capacitor banks correct a low power factor?
Capacitors supply leading reactive power (kVAR) locally at the facility, cancelling out the lagging inductive reactive power demanded by motors so the utility grid only needs to supply real working power.
Why not correct the power factor all the way to 1.0 (unity)?
Correcting to exactly 1.0 or leading PF increases the risk of harmonic resonance and overvoltage conditions when plant loads fluctuate. Target power factors between 0.95 and 0.98 are industry standard.
Does power factor correction reduce electricity kWh consumption?
PFC primarily reduces apparent power (kVA demand) and line current rather than active kWh consumption. However, it lowers utility maximum demand charges, eliminates PF penalties, and reduces internal cable heating losses.
How we compare
| Feature | Online Tool Store | Electrical manufacturer charts | Textbook lookup tables |
|---|---|---|---|
| Exact kVAR and µF capacitance calculation | ✓ | ✓ | ✗ |
| Instant line current (Amps) reduction | ✓ | ✗ | ✗ |
| Full power triangle before/after comparison | ✓ | Partial | ✗ |