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Power Factor Calculator

Find a load's power factor and how much correction it needs.

  • Free
  • No sign-up
  • Nothing is sent or stored
I know the
W
V
A

Shows the capacitor reactive power needed to correct to this value.

Result

Power factor
0.8282
Poor — consider correction
Apparent power (S)
4,830 VA
Reactive power (Q)
2,707.19 var
Phase angle (φ)
34.09°
Correction to 0.95
1,392.46 var of capacitors
How it was calculated
  1. PF = P ÷ S
  2. Q = √(S² − P²)
  3. φ = arccos(PF)

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved.

How to use the Power Factor Calculator

  1. Choose real power with voltage and current, or real and apparent power.
  2. Enter the values and the supply type.
  3. Read the power factor and the correction needed for your target.

What does this tool do?

Power factor is the ratio of real power (doing useful work) to apparent power (what the supply delivers). Motors and transformers draw reactive power, lowering the power factor and increasing current.

Adding capacitors supplies reactive power locally, raising the power factor. The calculator shows the kVAR needed to reach a target such as 0.95.

Why use it?

  • Single- and three-phase.
  • Correction capacitance in var.
  • Phase angle shown.

The formula

PF = P ÷ S
Q = √(S² − P²)
Q_c = P (tan φ₁ − tan φ₂)

Accuracy and limits

  • For learning and quick checks. Real engineering decisions should be verified by a qualified professional.

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed by the M2Toolkit team.

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