EngineerHub.orgHow to use this calculator
Select DC, single-phase or three-phase, then enter voltage, current and power factor from the equipment nameplate or measurement.
Inputs
Results
Background
Engineering basis, equations, assumptions, interpretation and practical limitations for this calculator.
Single-phase: P = V × I × PF
Balanced three-phase: P = √3 × VLL × I × PF
For three-phase systems, enter line-to-line voltage. For single-phase systems, enter the voltage across the load.
Frequently Asked Questions
Practical questions about assumptions, inputs, interpretation and limitations.
kW is active power that performs useful work, while kVA is apparent power supplied by the electrical system. In AC circuits, power factor relates the two: kW = kVA × power factor.
The familiar √3 formula applies when line-to-line voltage and line current are used for a balanced three-phase system. Different quantities or unbalanced systems require different treatment.
kvar is reactive power. It represents the oscillating exchange of energy associated with inductive or capacitive loads and combines with active power to form apparent power.
For the same active power, a lower power factor requires higher current and apparent power. That can increase conductor losses and affect transformer, generator and cable loading.
No. It calculates electrical power relationships only. Equipment and conductor sizing require additional checks such as current rating, starting duty, fault levels, installation conditions and governing electrical standards.