Power factor calculator
Calculate power factor and reactive power from real power and apparent power inputs.
What this calculator covers
Use this calculator when you need to compare real work against apparent electrical demand and want the power triangle spelled out.
Power factor is most useful as a diagnostic measure. Lower values mean more current is circulating for the same real power output, which can matter in system sizing and utility analysis.
Frequently asked questions
- What does a power factor of 1.0 mean?
- A power factor of 1.0, sometimes called unity power factor, means all of the apparent power supplied to the load is converted into useful real work. In practice, most inductive loads such as motors and transformers have a power factor below 1.0 because some current cycles back and forth without doing work.
- What is reactive power and why does it matter?
- Reactive power (measured in kVAR) is the portion of apparent power that oscillates between the source and the load without performing useful work. It does not show up on a wattmeter but still flows through conductors, which can increase losses and require larger wiring and equipment in a facility.
- How do I enter apparent power if I only know voltage and current?
- Switch the input mode to voltage and current, then enter the voltage, the current in amps, and select whether the system is single-phase or three-phase. The calculator derives apparent power as V × I for single-phase or √3 × V × I for three-phase, then divides by 1000 to express it in kVA.
- Should I consult an electrician before correcting a low power factor?
- Yes. Power factor correction typically involves installing capacitor banks or other equipment, and the sizing, placement, and safety requirements depend on the specific installation. This calculator is an estimating aid, not a substitute for a licensed electrical assessment.
Tool
Run the calculation
Result
RESULT · POWER FACTOR
â„–194
Primary result
0.900 PF
With 9.00 kW of real power and 10.00 kVA of apparent power, the power factor is 0.900.
- Power factor
- 0.9000
- Power factor percent
- 90.00%
- Apparent power
- 10.00 kVA
- Reactive power
- 4.36 kVAR
Step-by-step solution
- 1.Determine apparent power either directly from the entered kVA value or from voltage and current using sqrt(3) x V x I.
- 2.Compute power factor as real power divided by apparent power: 9.00 / 10.00.
- 3.Use the power triangle to back out reactive power, showing how far the load sits from unity power factor.
Walkthrough
Visual walkthrough
Power factor compares the real work a load does against the total apparent power the system has to supply.
01
Measure the real power
9.00 kW
Real power is the portion that actually becomes heat, motion, light, or other useful work.
02
Find apparent power
10.00 kVA
Apparent power is either entered directly or derived from voltage and current.
03
Divide real power by apparent power
A value closer to 1.0 means more of the supplied apparent power becomes useful work instead of reactive circulation.
0.900 PF