How to calculate Electrical Power?

Active power is W=VI (Voltage x Current) in single phase case.

Three phase power=1.xvoltagexcurrentxpower factor.

Electrical power equation:

  P = I × V = R × I2 = V2 ⁄ R where power P is in watts, voltage V is in volts and current I is in amperes (DC).  If there is AC, look also at the power factor PF = cos φ and φ = power factor angle  (phase angle) between voltage and amperage.

power means combination of two things voltage and current Explem if you have one load and run with load1 meter that's a power