Power factor measures how efficiently electrical power is converted to useful work. Low PF means more current is needed for the same power output, increasing losses and costs.
Power Factor Calculator
Our power factor calculator helps electrical engineers and facility managers understand and optimize AC power systems. Calculate the relationship between real, reactive, and apparent power, determine capacitor requirements for PF correction, and reduce electricity costs from power factor penalties.
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Updated: April 2025
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kW
kVA
V
Results
0.75
Power Factor (75%)
Real Power
100 kW
Reactive Power
88.19 kVAR
Apparent Power
133.33 kVA
Phase Angle
41.41°
Line Current
160.4 A
Capacitor Needed
55.26 kVAR
Current Reduction
21.05%
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electric_meter Power Factor Rating
Excellent
0.95 - 1.0
Good
0.85 - 0.95
Average
0.70 - 0.85
Poor
< 0.70
bolt Typical PF Values
Resistive Load
1.0
Induction Motor
0.7-0.85
Fluorescent Lights
0.5-0.6
How to Use This Calculator
1
Select Mode
Choose to calculate PF, power values, or correction requirements
2
Enter Power Data
Input real power (kW) and apparent power (kVA) or existing PF
3
Set Target PF
For correction mode, enter desired power factor
4
View Results
See all power values and capacitor sizing if applicable
The Formula
Power factor indicates how effectively electrical power is used. PF = 1 (unity) means all power does useful work. Low PF means reactive power is wasted. S² = P² + Q² (power triangle).
Power Factor (PF) = Real Power (kW) ÷ Apparent Power (kVA)
lightbulb Variables Explained
- PF Power Factor (0 to 1, or 0% to 100%)
- P Real Power in kW (actual work done)
- Q Reactive Power in kVAR (energy stored/returned)
- S Apparent Power in kVA (total power flow)
- θ Phase angle between voltage and current
tips_and_updates Pro Tips
1
Unity (1.0) power factor means 100% efficient power use
2
Industrial facilities aim for PF > 0.95 to avoid utility penalties
3
Motors and transformers cause lagging (inductive) power factor
4
Capacitors correct lagging PF; inductors correct leading PF
5
Oversized motors running at light load have poor PF
6
LED and VFD loads may have leading PF
7
Power factor correction reduces electricity bills and line losses
Improving PF reduces utility bills, decreases line losses, increases system capacity, and avoids penalty charges. Typical target is 0.95 or higher.
Frequently Asked Questions
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Data sourced from trusted institutions
All formulas verified against official standards.