Can this calculate kVAr from kW and PF?

Yes. Select the kW plus PF basis and enter real power and power factor.

Can this calculate kVAr from kW and kVA?

Yes. Select the kW plus kVA basis and enter real and apparent power values from the same condition.

What if kW is greater than kVA?

The calculator rejects that relationship because apparent power must be at least real power.

Does this size capacitors?

No. It calculates a reactive-power record and does not select capacitor equipment or correction stages.

Why is low PF flagged?

Low PF makes the reactive component large, so the metering value and operating condition should be checked before using the result.

Reactive power kVAr calculator

Q = sqrt(S^2 - P^2); from kW and PF, S = P / PF; from kW and kVA, PF = P / S

Real power is entered in kW.
Apparent power is entered in kVA when the kW plus kVA basis is selected.
Power factor is entered when the kW plus PF basis is selected.
The calculator flags very low PF for review but does not size correction equipment.

Formula variables
Variable	Meaning	Unit	Use
P	Real power	kW	Entered real power.
S	Apparent power	kVA	Entered or derived apparent power.
PF	Power factor	ratio	Entered or derived power factor.
Q	Reactive power	kVAr	Reactive side of the power triangle.
Angle	Power factor angle	degrees	Arccos of the power factor.

Reactive power kVAr calculator technical guide

Calculate Australian reactive power in kVAr from entered kW with power factor or entered kW with kVA values.

Use this calculator when the immediate question is the reactive-power side of a power triangle. It accepts either kW with power factor, or kW with kVA, and returns kVAr, derived kVA or derived PF, and the PF angle. The output can support Australian power-factor notes, tariff context, plant load records and staged correction discussions.

The calculator is not a correction design tool. It does not size capacitors, choose detuned reactors, check harmonics, assess resonance, evaluate switching controls or confirm manufacturer suitability. It keeps one kVAr relationship visible so the source values can be reviewed.

Reactive Power Use Cases

Reactive power use cases
Work situation	Entered basis	Useful output	Outside the result
Power-factor worksheet	kW and measured PF	Derived kVA and kVAr	Correction equipment selection
Metering summary	kW and kVA	Derived PF and kVAr	Meter accuracy or load profiling
Tariff context	Real power and PF from a billing note	Reactive component for discussion	Retailer bill interpretation
Capacitor staging handoff	Required or measured reactive component	kVAr value for a staging worksheet	Stage selection or detuning
Plant review	Low PF load value	Review note beside kVAr	Harmonic or resonance study

A useful reactive-power record keeps kW, kVA or PF values tied to the same load condition. A weak record mixes a real-power value from one period with a power factor from another.

Power Triangle Boundary

Reactive power boundary
Included in this calculator	Not included in this calculator
kW plus PF input basis	Capacitor equipment selection
kW plus kVA input basis	Harmonic analysis or resonance assessment
Derived kVA, PF, kVAr and PF angle	Detuned reactor or switching-control design
Invalid relationship check when kVA is below kW	Bill interpretation or tariff recommendation
Low-PF review note	Site approval or manufacturer confirmation

The boundary matters because kVAr is only one side of a broader correction and power-quality question. The result can support a review, but it cannot decide what equipment should be installed.

Input Checklist

Values to collect before calculating kVAr
Input	Strong basis	Weak basis
Reactive reference	Load, meter, switchboard or correction worksheet	Generic note with no project context
Input basis	Clear choice between kW plus PF or kW plus kVA	Values copied without knowing what is known
Real power	kW value for the same load condition	Estimated kW from another period
Apparent power	kVA value paired with the kW value	kVA from a different meter or load
Power factor	PF for the same load condition	Assumed PF with no source

If the values are measured, keep the measurement period and instrument context with the result. If the values are design assumptions, record the source and the operating state being represented.

Review Workflow

Name the load, meter, correction worksheet or switchboard record.
Choose whether the known inputs are kW plus PF or kW plus kVA.
Enter real power in kW.
Enter PF or kVA from the same operating condition.
Read kVAr, derived kVA or PF, and PF angle together.
If PF is very low, check the measurement and load condition before using the record.
Move to capacitor bank staging only when a staged equipment comparison is the next question.
Keep harmonics, resonance and manufacturer suitability outside this simple power-triangle record.

The workflow is intentionally transparent. It calculates a relationship; it does not hide correction design decisions inside a formula page.

Worked Australian Examples

Reactive power examples
Situation	Inputs	Output reading	Practical note
kW and PF record	250 kW and PF 0.82	304.88 kVA and 174.50 kVAr	Good for a reactive component note.
kW and kVA record	180 kW and 225 kVA	PF 0.80 and 135.00 kVAr	Keep kW and kVA source period together.
Low PF review	160 kW and PF 0.66	High kVAr with a review note	Check metering and load condition first.

These examples use standard power-triangle arithmetic and do not decide correction equipment or tariff outcomes.

Related Tools

Use the kVA, kW and power factor calculator when the task is a broader two-value conversion. Use the capacitor bank staging calculator when a required correction value needs to be compared with entered stage sizes. Use the power-factor relationship chart when the user needs the relationship explained rather than calculated.

Next tool selection
Next question	Use next
General kVA, kW and PF conversion	kVA, kW and power factor calculator
Entered capacitor stages must be compared	Capacitor bank staging calculator
Three-phase current is also known	Three-phase power matrix calculator
Power triangle needs explanation	Power-factor relationship chart

Stop Points

kW and kVA values do not belong to the same operating condition.
kVA is lower than kW.
PF is assumed without a source or measurement basis.
Harmonics, resonance or switching are material to the decision.
The result is being used to select correction equipment without further review.

Export the result only with the input source, operating condition and intended next use. The kVAr value is a relationship output, not a complete power-quality decision.

Reference: KVAR-1
Input basis: kw-pf
Real power: 250 kW
PF or kVA: 0.82

Apparent power304.88 kVA
Power factor0.82
Reactive power174.5 kVAr

Reactive power174.5 kVAr

304.88 kVA at PF 0.82.

The result derives the apparent power and kVAr side of the power triangle for the entered operating point.

Real power is entered in kW.
Power factor is the measured or documented value for the same operating point.
Equipment selection is outside this calculator.

Reference: KVAR-2
Input basis: kw-kva
Real power: 180 kW
PF or kVA: 225 kVA

Apparent power225 kVA
Power factor0.8
Reactive power135 kVAr

Reactive power135 kVAr

225 kVA at PF 0.8.

The kVAr value follows from the power triangle when real power is less than apparent power.

kW and kVA are for the same load and period.
The derived PF is a relationship value.
Metering uncertainty remains outside the calculation.

Reference: KVAR-3
Input basis: kw-pf
Real power: 160 kW
PF or kVA: 0.66

Apparent power242.42 kVA
Power factor0.66
Reactive power182.12 kVAr

Reactive power182.12 kVAr

242.42 kVA at PF 0.66.

The page calculates the reactive value but flags the low PF input for metering and load-condition review.

The PF value is entered from a documented source.
The calculator does not model harmonics or resonance.
Correction staging should use a separate worksheet.