Power Factor Correction Calculator, for Lagging Power Factor

kVAR of PF Correction Capacitor = kW X [(tan(cos^-1(OLD PF))) - (tan(cos^-1(NEW PF)))]

Kilowatts, "kW"
Original Power Factor, "OLD PF"

I recommend measuring kW using a power meter. You will have better results choosing a power factor correction capacitor for your motor, especially if it is not fully loaded. But, if you don't have a meter, you can estimate kW with this formula.

kW = (HP X 0.746) / Eff.

Horse Power "HP"
Efficiency, "Eff."