Power Factor Calculator
PF = W ÷ (V×A) or W ÷ VA, clamped 0–1. Click any i for detail.
Power readings
Real power (W)
i
W
True power in watts. |
|
|---|---|
Voltage (V)
i
V
RMS voltage. |
|
Current (A)
i
A
RMS current. |
|
Apparent power VA (optional)
i
VA
If > 0, used instead of V×A. |
How to use this calculator
- Enter real power in watts.
- Enter V and A, or a known VA.
- Leave VA at 0 to use V×A.
- Read PF and apparent power.
Results explained
Power factor is real power divided by apparent power. For a simple single-phase sketch, apparent power ≈ V×A (or a measured VA). PF is clamped between 0 and 1 on this page.
Quick reference: PF
PF = W / VA; VA ≈ V×A (or entered).
| Item | Detail |
|---|---|
| PF 1.0 | Resistive ideal |
| PF < 1 | Reactive / distortion |
| VA from W/PF | W ÷ PF |
| Three-phase | Different √3 factors |
Single-phase educational sketch — not a utility bill analyzer.
How the estimate is built
apparent = VA>0 ? VA : V×A; PF = clamp(W/apparent, 0, 1).
Example scenario
800 W, 120 V, 10 A → PF = 0.667.
FAQ
Leading vs lagging?
Sign/phase not shown — magnitude only.
Three-phase?
See the three-phase power calculator.
Why clamp at 1?
Measurement noise can push W > VA slightly.
Correcting PF?
Capacitors/reactors need a design — not sized here.