AC Power Calculator (Single & Three Phase)
Calculate real (W), reactive (VAR) and apparent (VA) power and phase angle for single- or three phase loads from voltage, current and power factor.
Runs on your device
Result
Results appear here as you type.
What it does
For single phase, S = V·I. For a balanced three phase load with line voltage and line current, S = √3·V·I. Then P = S·pf and Q = S·sin(θ).
How to use it
- Choose single or three phase.
- Enter voltage, current and power factor.
- Read P, Q, S and θ.
Example
The example fills in realistic values and runs the tool. Select Try an example above to see it.
When it helps
- Sizing generators and UPS units.
- Power systems coursework.
- Checking motor nameplate data.
Questions
Which voltage for three phase?
Line to line voltage, for example 400 V in Pakistan and much of Europe, or 208/480 V in North America.
Is the load leading or lagging?
The magnitudes are the same either way; the sign of Q depends on whether the load is inductive (lagging) or capacitive (leading).
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