Metric Republic / Electrical engineering / Power Factor Correction Capacitor Calculator

Power Factor Correction Capacitor Calculator

Calculate required capacitor kVAr to improve from an existing to a target power factor.

Updated September 2026

How it works

Calculate required capacitor kVAr to improve from an existing to a target power factor.

Formula:
Qc = P·[tan(arccos PF1) − tan(arccos PF2)].

Before you use the result: Check switching steps, harmonics, resonance, voltage and utility requirements before equipment selection.

Practical use

Use verified material data and project geometry. Treat results as planning estimates and compare them with the energy/thermal requirements that apply to the project.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

How to use this calculator: Power Factor Correction Capacitor Calculator

Calculate required capacitor kVAr to improve from an existing to a target power factor.

Quick workflow

Enter the project values from the latest drawing, specification or verified site measurement.
Check units, material properties, allowances and any code- or supplier-specific parameters before calculating.
Review the result together with the formula, assumptions and the related checks shown on this page.

Worked example

Example inputs: Real power P [kW]: 100; Existing power factor: 0.75; Target power factor: 0.95.

Using the sample values built into the calculator, the calculation gives approximately: Existing reactive power: 88.19 kVAr; Target reactive power: 32.87 kVAr; Required capacitor power: 55.32 kVAr.

What the result means

Calculation method: Qc = P·[tan(arccos PF1) − tan(arccos PF2)].

Before using the result: Check switching steps, harmonics, resonance, voltage and utility requirements before equipment selection.

Common questions

What does this calculator do?

Calculate required capacitor kVAr to improve from an existing to a target power factor.

Which inputs should I verify?

Key inputs to verify include: Real power P [kW], Existing power factor, Target power factor.

Can I use this result for final design or ordering?

Use the result as a transparent planning or checking aid. Final design, code compliance, supplier selection and project-specific decisions still need to be verified where applicable. Check switching steps, harmonics, resonance, voltage and utility requirements before equipment selection.

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