Power Factor Calculator
Calculate power factor, real power, apparent power, reactive power, phase angle, current, and efficiency for AC electrical systems.
Calculation Mode
Input Values
Power Factor Result
Power Factor
0.800
80.0% Lagging
Real Power
0 kW
Reactive Power
0 kvar
Apparent Power
0 kVA
Phase Angle
0°
Current
—
Efficiency
—
PF Percentage
80.0%
Power Triangle
PQS
S²=P² + Q²
Calculation Steps
Enter values and click Calculate.
Power Factor Formulas
Power Factor:
PF=P / S
PF=P / S
Apparent Power:
S=√(P² + Q²)
S=√(P² + Q²)
Reactive Power:
Q=√(S² − P²)
Q=√(S² − P²)
Real Power:
P=S × PF
P=S × PF
Phase Angle:
θ=cos⁻¹(PF)
θ=cos⁻¹(PF)
Single-Phase Power:
P=V × I × PF
P=V × I × PF
Three-Phase Power:
P=√3 × VL× IL× PF
P=√3 × VL× IL× PF
Example Calculation
Suppose an AC system has 100 kWof real power and 125 kVAof apparent power.
PF=P / S
PF=100 / 125
PF=0.80
PF=100 / 125
PF=0.80
The system therefore has a power factor of 0.80, or 80%.
What Is Power Factor?
Power factor describes how effectively electrical power is converted into useful work in an AC electrical system.
It is the ratio of real power, measured in watts, to apparent power, measured in volt-amperes.
PF=Real Power / Apparent Power
A power factor close to 1 indicates that most of the supplied apparent power is being converted into useful real power.
Inductive loads such as motors and transformers commonly produce lagging power factor, while capacitive loads can produce leading power factor.