Transmission & Grid calculator
Three-Phase Power Calculator
Convert between current, kW, kVA and kVAR for three-phase or single-phase systems at any voltage and power factor.
GridBasis: IEEE Std 100 definitions · IEC 60050
Results
- Enter values to calculate
- —
Formula
Three-phase: S = √3 · VLL · I Single-phase: S = V · I
P = S · PF Q = S · sin(arccos PF) S² = P² + Q²
Sapparent power (VA),Preal power (W),Qreactive power (var)VLLline-to-line voltage,PFdisplacement power factor
Worked example
480 V three-phase load drawing 100 A at 0.85 power factor: S = 1.732 × 480 × 100 = 83.1 kVA, P = 83.1 × 0.85 = 70.7 kW, Q = 83.1 × 0.527 = 43.8 kvar.
Assumptions and standards
- Balanced, sinusoidal system. Harmonics are not included; with non-linear loads the true power factor is lower than the displacement power factor.
- Three-phase voltage is line-to-line.
Formula and data last verified: October 2026.
Frequently asked questions
What is the difference between kW and kVA?
kW is real power that does work. kVA is apparent power, the product of voltage and current, which sizes cables, transformers and generators. They are related by the power factor: kW = kVA × PF.
Where does √3 come from?
In a balanced three-phase system, line-to-line voltage is √3 times the line-to-neutral voltage, so total power equals √3 × V(line-to-line) × I.
Can I use these results for final design?
Use them for preliminary design and checking. Final designs must be verified by a qualified engineer against the code edition and standards adopted where the work is installed.
Is my data sent anywhere?
No. Every calculation runs in your browser. Nothing you type is uploaded or stored on our servers.