Electrical basics
Amps to kW calculator
Enter the current you measured with a clamp meter, the voltage, the power factor and the number of phases to see approximate active and apparent power.
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How is it calculated?
Apparent power is voltage times current; three phase adds a √3 factor. Active power is apparent power times the power factor.
Apparent power
S = k × U × I / 1000
k = 1 (single phase, U: line-to-neutral) or √3 (three phase, U: line-to-line); U: voltage (V), I: current (A), S: kVA.
Active power
P = S × cos φ
P: active power (kW), cos φ: power factor.
Example
- Three phase: I = 32 A, U = 400 V, cos φ = 0.85 → S ≈ 22.2 kVA, P ≈ 18.8 kW.
- Single phase: I = 16 A, U = 230 V, cos φ = 1 → S = P ≈ 3.68 kW.
The example inputs are for illustration only; they are not verified defaults. Results are approximate and do not replace engineering advice.
Frequently asked questions
Which current do I enter for three phase?
For a balanced load, enter the line current of one phase. If the phase currents differ, the result is rough; measuring each phase is more accurate.
What if I do not know the power factor?
Check the nameplate or a power analyser. If you enter an estimate, the result is only as good as that estimate.
Does this give the energy on my bill?
No. This is instantaneous power. Energy (kWh) is power times operating time; use the appliance consumption calculator for that.