Power Factor Calculator
Calculate AC power components from voltage, current, and phase angle.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Enter the RMS voltage, RMS current, and phase angle between them. The calculator shows the power factor, real power, reactive power, and apparent power.
About Power Factor
In AC circuits, voltage and current may not be in phase, meaning not all the power delivered is useful. The power factor (cos phi) indicates the fraction of apparent power that performs real work. Real power (W) does useful work, reactive power (VAR) oscillates without doing work, and apparent power (VA) is the product of RMS voltage and current. Power factor correction is important in industrial and commercial electrical systems to reduce losses and costs.
Frequently Asked Questions
What is power factor?
Power factor is the cosine of the phase angle between voltage and current in an AC circuit. It ranges from 0 to 1. A power factor of 1 means all power is real (useful) power.
Why is power factor important?
Low power factor means more current is needed to deliver the same real power, increasing energy losses and requiring larger wires and transformers. Utilities may charge penalties for low power factor.
What is the difference between real and reactive power?
Real power (watts) does actual work. Reactive power (VAR) oscillates between source and load in inductive or capacitive circuits, doing no net work but still requiring current flow.