Power Factor Correction Calculator

Power factor correction reduces wasted energy in AC electrical systems by adding capacitors to offset reactive power — the Power Factor Correction Calculator tells you exactly what size capacitor bank you need. Select your system type (single or three phase), frequency, and connection type, then enter your voltage, real power, current power factor, and target power factor to get the required capacitor size in µF. Secondary outputs include required reactive power (kVAR), current and corrected apparent power, and both power angles.

System Type *

Connection Type *

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Results

Required Capacitor Size

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Required Reactive Power (Qc)

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Current Apparent Power

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Corrected Apparent Power

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Current Power Angle

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Corrected Power Angle

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Frequently Asked Questions

What is power factor correction and why is it important?

Power factor correction improves the efficiency of electrical systems by reducing reactive power. It lowers energy costs, reduces equipment stress, and improves voltage stability in industrial applications.

Why is accurate capacitor bank sizing required?

Proper sizing prevents over-correction (leading power factor), reduces harmonic distortion, and ensures optimal system performance. Under-sized capacitors won't provide sufficient correction, while over-sized ones can cause voltage regulation issues.

What causes low power factor in electrical systems?

Inductive loads like motors, transformers, and fluorescent lighting are the main causes. These devices draw reactive power, causing current to lag behind voltage and reducing the power factor.

What's the difference between single-phase and three-phase correction?

Three-phase systems require capacitors connected to each phase or in delta configuration. The capacitor sizing calculation differs, with three-phase systems typically requiring larger total capacitance but distributed across phases.

What is the optimal target power factor?

Most utilities recommend a power factor between 0.90-0.95. Going higher than 0.95 may cause over-correction and leading power factor, which can be penalized by some utilities.

How do I connect power factor correction capacitors?

Capacitors should be connected in parallel to the load. For motors, they can be connected directly across motor terminals or at the motor control center for multiple loads.

What is reactive power (kVAR) and how is it calculated?

Reactive power is the power that oscillates between source and load without doing useful work. It's calculated as Q = P × tan(φ), where P is real power and φ is the power angle.

How often should I check my power factor?

Monitor power factor monthly through utility bills or power quality meters. Significant changes may indicate equipment issues, load changes, or capacitor failures requiring attention.