Power Factor Calculator

Power factor is the ratio of the power that does the work to the power the supply has to deliver. When it slips, the same job drags more current — heating cables, squeezing transformers and pulling penalty tariffs from the utility.

Power Factor Calculator derives the pf from your kW and kVA (or from volts, amps and watts), then sizes the capacitor bank needed to lift it to your target with a practical margin.

Everything runs in the browser; nothing is uploaded.

• Two input paths: kW / kVA, or volts / amps / watts.
• Single and three-phase: Phase selection adjusts the calculation.
• Correction sizing: kVAr required to reach your target pf.
• Margin control: A standard 15% oversizing step built in.
• Angle and triangle: Angle phi and the kW / kVAr / kVA sides shown.
• Export: Copy or download as text, CSV or JSON.
• Learning guide: Why the grid charges for bad power factor.

1. Choose the input mode — kW/kVA or V/A/W.
2. Enter your figures and select the phase system.
3. Set the target pf you want to reach (commonly 0.95).
4. Read the current pf and the kVAr of correction needed.
5. Graduate the capacitor bank accordingly.
6. Export the correction size if needed.

Example 1 — From kW/kVA. 80 kW over 100 kVA gives pf 0.8.

Example 2 — From V/A/W. 230 V, 10 A, 2,070 W on single-phase: pf 0.9.

Example 3 — Correction. Lifting 0.7 to 0.95 at 120 kW needs about 93 kVAr of capacitance.

Example 4 — Three-phase. A 400 V motor drawing 25 A per phase at 13.9 kW runs at pf 0.8.

• See the gap: Current pf made explicit from your own numbers.
• Sizes the fix: Capacitor kVAr estimated with headroom.
• Single and three-phase: Both systems handled correctly.
• Explained maths: Angle, triangle and formula all live.
• Free and private: No uploads, no accounts, no logging.