Converting voltage to power measured in watts is easy using a simple Watt’s Law formula. Watt’s Law states that current is equal to power divided by voltage. Using a little algebra we can change this formula a bit to also state that power is equal to voltage times current.

The real power P in watts (W) is equal to the apparent power S in volt-amps (VA), times the power factor PF:

P_(W) =  S_(VA) × PF

Example

What is the real power in watts when the apparent power is 3000 VA and the power factor is 0.8?

Solution:

P = 3000VA × 0.8 = 2400W