Is reactive power positive or negative?

This version reports magnitude. Sign conventions depend on leading vs lagging loads.

What is a good power factor?

Utilities often want PF above 0.9. Check your utility contract for penalty thresholds.

Can I enter leading/lagging?

Not explicitly. PF here is magnitude; note your load type separately.

How do harmonics affect PF?

This calculator ignores distortion power. Harmonics can lower true power factor beyond simple displacement.

Single-phase vs three-phase?

Use total kW/kVA for the system. The math is the same; ensure values are consistent.

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Power Factor Calculator

Calculate power factor and reactive power from real and apparent power.

Results

Power factor: 0.83
Reactive power (kVAR): 3.32

How to use this calculator

Enter real power (kW) and apparent power (kVA).
We compute power factor and reactive power (kVAR).
Use the results to check efficiency or capacitor sizing.

Inputs explained

Real power (kW): Active power actually doing work.
Apparent power (kVA): Total power drawn (vector sum of real and reactive).

How it works

PF = kW ÷ kVA. Reactive power (kVAR) = √(kVA² − kW²).

Formula

PF = P ÷ S
Q = √(S² − P²)

When to use it

Checking if a facility is incurring low power factor penalties.
Sizing power factor correction capacitors.
Evaluating load characteristics for generator/UPS sizing.

Tips & cautions

PF near 1 is efficient. Inductive loads (motors) lower PF; capacitors can correct it.
Ensure kW and kVA are for the same load and measurement interval.
For three-phase systems, input total kW/kVA across phases.
Assumes steady-state values; highly dynamic loads need more detailed analysis.
Does not differentiate leading vs lagging PF—reactive power sign is magnitude only.
Harmonics and distortion power aren’t modeled.

Worked examples

5 kW load at 6 kVA

PF ≈ 0.83
Reactive ≈ 3.32 kVAR

Unity power factor

If kW = kVA, PF = 1 (purely resistive load).

Deep dive

This power factor calculator finds PF and reactive power from real power (kW) and apparent power (kVA). Enter kW and kVA to see efficiency and kVAR instantly.

Use it to spot low PF penalties, plan capacitor correction, or size generators/UPS systems. Leading/lagging sign conventions aren’t shown; kVAR is magnitude.

FAQs

Is reactive power positive or negative?: This version reports magnitude. Sign conventions depend on leading vs lagging loads.
What is a good power factor?: Utilities often want PF above 0.9. Check your utility contract for penalty thresholds.
Can I enter leading/lagging?: Not explicitly. PF here is magnitude; note your load type separately.
How do harmonics affect PF?: This calculator ignores distortion power. Harmonics can lower true power factor beyond simple displacement.
Single-phase vs three-phase?: Use total kW/kVA for the system. The math is the same; ensure values are consistent.

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