About electrical power calculator
Electrical power tells you how fast energy is used. The calculator gives real, apparent and reactive power for single-phase and three-phase systems.
The three kinds
- Real power (kW) does the actual work.
- Apparent power (kVA) is voltage × current.
- Reactive power (kVAR) moves back and forth in coils and motors.
- Power factor = real power ÷ apparent power.
Formulas
Single phase: P = V × I × PF. Three phase: P = √3 × V × I × PF using line values.
A worked example
A single-phase load on 230 V draws 10 A at a power factor of 0.8. The apparent power is 2,300 VA, the real power is 2,300 × 0.8 = 1,840 W and the reactive power is √(2,300² − 1,840²) = 1,380 VAR.
Why power factor matters
A low power factor means you draw more current for the same useful work, which wastes capacity and may lead to penalties for industrial users. Capacitors are commonly used to correct it.
