APFC kVAR Calculator
Calculate the reactive power needed to improve a load or installation from present power factor to target power factor.
How this calculator works
Qc = P × (tan(phi1) - tan(phi2)).
phi1 = arccos(existing PF) and phi2 = arccos(target PF). P is active load in kW and Qc is capacitor-bank requirement in kvar.
Example
For a fixed kW load, improving PF from 0.80 to 0.98 reduces the reactive power drawn from the supply and lowers kVA demand.
Source and engineering note
Schneider Electric gives the power-factor-correction relationship as Qc = P × (tan phi1 - tan phi2), where P is active power in kW and Qc is required capacitor power in kvar.
For systems with significant harmonics or resonance risk, capacitor-bank selection may require detuned reactors or another engineered solution.
Schneider Electric power factor correction guidance
Last reviewed: 27 August 2026.
Frequently asked questions
Can target PF be lower than current PF?
No correction is required if the target is equal to or lower than the existing PF.
Should I install exactly the calculated kvar?
The result is the theoretical requirement. Practical APFC banks use steps and must consider load variation and overcorrection.
What if the system has VFDs, UPS or harmonics?
Harmonic conditions can require detuned or filtered capacitor-bank solutions. Do not select a plain capacitor bank from kvar alone.