Power Factor Calculator
Calculate power factor, real power, apparent power, reactive power, and the required capacitor bank for power factor correction in single-phase or three-phase AC circuits.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Power Factor Calculator
This calculator computes power factor (PF), real power (P), apparent power (S), reactive power (Q), and optionally the capacitor bank needed for power factor correction.
Step 1: Select System Type
- Single-Phase or Three-Phase — choose based on your electrical system.
Step 2: Choose Known Values
- P, V, I — enter Real Power (W), Voltage (V), and Current (A).
- P, V, PF — enter Real Power (W), Voltage (V), and Power Factor (0–1).
- S, P — enter Apparent Power (VA) and Real Power (W). The third input is optional.
Step 3: Enter Values
- All inputs must be positive numbers. Use decimal points if needed (e.g., 0.95).
- For P, V, PF or S, P, you can optionally set a Target Power Factor (0–1) and Frequency (Hz, typically 50 or 60) to calculate the required capacitor bank.
Step 4: Click "Calculate"
- Results show PF, P, S, Q, and if applicable, the capacitor bank size in kvar and capacitance in µF.
- The formula used is displayed below the results for reference.
Tip: Ensure the target PF is higher than the current PF to enable correction. All values are in metric units (W, V, A, VA, var, Hz).
Previous Results
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Frequently Asked Questions
Power factor is the ratio of real power (P) to apparent power (S) in an AC circuit, ranging from 0 to 1. It indicates how effectively electrical power is being used.
Improving power factor reduces reactive power, lowers electricity bills, increases system capacity, and reduces line losses. Utilities often charge penalties for low power factor.
Select the system type (single or three-phase) and the known values you have. Enter the required values and optionally a target power factor and frequency to get the capacitor bank size.