Power Factor Correction Calculator and kW Calculator
A free power factor correction calculator and kW calculator that sizes a capacitor bank in kVAR to lift your power factor from the current value to a target (typically 0.95). It reports per-phase kVAR, capacitor microfarads for both wye and delta connections, and an estimate of the demand-charge savings on your utility bill.
Check utility bill or measure with power analyzer
Recommended: 0.95 (avoid over-correction)
Need this validated by a licensed PE?
A free calculator gets you in the ballpark. For permit-stamped, defensible work, ClarkTE delivers a PE-stamped power factor correction sizing study from a working engineer — typically within 48 hours of receiving your one-line and load data.
Formulas Used
Benefits of Power Factor Correction
- Reduces utility demand charges (kVA-based billing)
- Decreases line losses (I²R losses) in your distribution system
- Increases system capacity without upgrading transformers/cables
- Improves voltage regulation and equipment performance
- May be required by utility to avoid penalty charges
- Typical ROI: 1-3 years for industrial/commercial facilities
- Target PF: 0.95 is recommended (avoid leading PF from over-correction)
- Use automatic capacitor banks for varying loads
- Size capacitors for 135% of rated voltage if harmonics present
- Consider harmonic filters if significant non-linear loads exist
Power factor: what is it, and why does it matter?
Power factor is the ratio of real power (kW, the kind that does work) to apparent power (kVA, the kind your transformer and conductors actually have to carry). A power factor of 1.0 means every amp of current is producing useful work. A power factor of 0.75 means roughly a quarter of your current is being shuffled back and forth as reactive power without doing anything for you.
Inductive loads — motors, transformers, fluorescent lighting ballasts, welders — pull lagging reactive power that drops the power factor. Capacitor banks supply leading reactive power that cancels the inductive component. The kW calculator above tells you exactly how many kVAR of capacitance you need to land at your target.
Why bother? Most utility tariffs above ~50 kW charge for demand based on kVA, not kW, or apply a power-factor penalty if you slip below 0.90. A 500 kW load at 0.75 PF draws 667 kVA. The same load at 0.95 PF draws 526 kVA. That 141 kVA delta is what shows up as monthly demand savings on the bill.
Sizing a real capacitor bank?
A calculator gets you in the ballpark. A real install needs a power-quality study (harmonics can kill capacitors), a verified peak-load profile, and protection coordination with the upstream feeder. ClarkTE handles all three under one PE stamp.
Power factor FAQ
What is power factor?
Power factor is the ratio of real power (kW) to apparent power (kVA). At PF = 1.0, every amp of current does useful work. At PF = 0.75, roughly a quarter of your current is reactive — getting shuffled back and forth without doing anything for you. Inductive loads (motors, transformers, fluorescent ballasts) pull lagging reactive power and drop PF.
What target power factor should I correct to?
0.95 is the standard target. Going higher (0.98+) risks leading PF if the load drops, which trips utility relays and damages equipment. Most utility tariffs penalize PF below 0.90 and bill on kVA above ~50 kW, so the savings curve flattens above 0.95.
Wye vs delta capacitor connection — which do I use?
For ≤ 600 V, wye is preferred: lower voltage rating, easier replacement, cleaner fault protection. For > 600 V industrial, delta is more common because the capacitors are 1/3 the µF for the same kVAR (due to V² in C = Q / (ωV²)). The calculator returns capacitance for both.