Power Factor Calculator
Enter real power and apparent power to calculate PF, phase angle, and reactive power. Optional voltage and phase settings estimate current demand.
Leave blank if you only need PF, angle, and reactive power.
Power Triangle
The power triangle links real power (P), reactive power (Q), and apparent power (S). PF = cos(phi).
How the Calculation Works
Power factor compares useful power (P) with total apparent power demand (S). A value near 1.00 means current is closely aligned with voltage. Lower values mean a larger share of current supports reactive power, which increases current draw without increasing useful output.
In the triangle model, real power is horizontal, reactive power is vertical, and apparent power is the hypotenuse. The phase angle (phi) is between real and apparent power. Inductive systems are usually lagging, while capacitive compensation can move the system toward leading.
Use this calculator to size correction efforts, compare operating conditions, and sanity-check measurements from meters. For current estimates, provide line voltage and phase type; the tool applies standard AC relationships. All math runs in your browser with no data sent anywhere.
Reference Ranges
| Power Factor | Typical Interpretation | Operational Notes |
|---|---|---|
| 0.95 to 1.00 | Excellent | Low reactive demand and efficient current use. |
| 0.90 to 0.95 | Good | Common target range for many commercial systems. |
| 0.80 to 0.90 | Fair | Can increase current and losses. Improvement may be worthwhile. |
| Below 0.80 | Poor | Often associated with larger losses and possible utility penalties. |
FAQ
Can power factor be negative?
In standard load analysis, PF is usually shown as a positive magnitude with a lagging or leading label. Direction is represented by that label rather than a negative sign.
Why does current rise when PF drops?
For fixed real power and voltage, lower PF means larger apparent power. Since current is tied to apparent power, required line current rises.
Is this suitable for harmonic-rich systems?
This tool focuses on displacement PF from basic power triangle relationships. Systems with strong harmonics may need true PF analysis from power quality instruments.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are computed using standard formulas and should be verified for critical applications.
Related Tools
- FOV Visualizer -- Visualize and calculate field of view angles for cameras, games, and VR
- Wavelength Calculator -- Convert between wavelength, frequency, and energy for electromagnetic waves
- HVAC BTU Calculator -- Calculate heating and cooling BTU requirements for any room size
- Electricity Usage Calculator -- Calculate power consumption, electricity costs, and energy usage for appliances
Related Tools
View all toolsOhm's Law Calculator
Compute voltage, current, or resistance
Resistor Color Code Calculator
Decode 4, 5, and 6 band resistor color codes to find resistance values
Power Law Calculator
Compute electrical power from voltage and current
Force Calculator
Calculate force from mass and acceleration
Kinetic Energy Calculator
Calculate kinetic energy, mass, or velocity with unit conversions
Potential Energy Calculator
Calculate gravitational potential energy, mass, or height with unit and gravity presets
Power Factor Calculator FAQ
What is power factor?
Power factor is the ratio of real power to apparent power in an AC system. It shows how effectively electrical power is converted into useful work.
How do you calculate power factor?
Power factor equals real power divided by apparent power. PF = P / S. For example, 8 kW divided by 10 kVA gives a power factor of 0.8.
What is the difference between lagging and leading power factor?
Lagging power factor usually indicates inductive loads like motors. Leading power factor usually indicates capacitive behavior, often from capacitor banks or over-correction.
Why does low power factor matter?
Low power factor means higher apparent power and current for the same real power. That can increase losses, voltage drop, and utility penalties in commercial systems.
Does this calculator store my values?
No. All calculations run locally in your browser and no values are sent to any server.