Power Factor Calculator
Calculate power factor from real and apparent power, or from phase angle.
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Introduction
Power Factor Calculator — Calculate power factor from real and apparent power, or from phase angle. Enter Real power (W), Apparent power (VA) to get an instant, accurate result.
Formula
PF = Real Power (W) ÷ Apparent Power (VA). If a phase angle (φ) between voltage and current is known instead, PF = cos(φ).
Step-by-step
- Enter the Real power (W).
- Enter the Apparent power (VA).
- Click Calculate to see your result instantly.
Real-world example
Example: With Real power (W) = 900, Apparent power (VA) = 1000, the Power Factor Calculator gives Power Factor: 0.9.
Frequently Asked Questions
What does a power factor less than 1 mean?
It means some of the apparent power (VA) delivered by the source is not being converted into useful work (real power, W) — the difference is reactive power, common with motors, transformers, and other inductive loads.
Can power factor be negative or greater than 1?
No — power factor for a physical load is bounded between 0 and 1; a leading or lagging phase relationship is described by whether current leads or lags voltage, not by the sign of PF itself.
What inputs does the Power Factor Calculator need?
You'll need to provide: Real power (W), Apparent power (VA). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Power Factor Calculator?
The Power Factor Calculator applies the formula exactly as calculated — PF = Real Power (W) ÷ Apparent Power (VA). If a phase angle (φ) between voltage and current is known instead, PF = cos(φ). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Power Factor Calculator free to use?
Yes, the Power Factor Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Power Factor Calculator
The Power Factor Calculator uses a real, verifiable formula — PF = Real Power (W) ÷ Apparent Power (VA). If a phase angle (φ) between voltage and current is known instead, PF = cos(φ). — so results are accurate every time, not an approximation.