⚡ Free Online Tool
Single & 3-Phase Power Calculator kW · kVA · kVAR · Current · Power Factor
Calculate active power, apparent power, reactive power, line current and phase angle for any single-phase or three-phase AC circuit — instantly, for free.
P = √3 · VL · IL · PF
S = P / PF
Q = √(S²−P²)
IEC Standard
AC Power
Input Parameters
Select phase, solve mode and enter known values
System Phase
Solve For
Active P
(kW)
(kW)
Apparent S
(kVA)
(kVA)
Reactive Q
(kVAR)
(kVAR)
Current I
(Amps)
(Amps)
Power Factor
(cosφ)
(cosφ)
Voltage
(Volts)
(Volts)
Known Values
Power Unit Scale
Result
Power Analysis
Single Phase AC
P — Active (kW)
Q — Reactive (kVAR)
S — Apparent (kVA)
Power Factor—
00.51.0
► Formulas — Single & 3-Phase
AC Power Formulas (IEC Standard)
Single Phase
S = V × I
P = V × I × cosφ
Q = V × I × sinφ
I = S / V
Three Phase
S = √3 × VL × IL
P = √3 × VL × IL × cosφ
Q = √3 × VL × IL × sinφ
I = S / (√3 × VL)
Power Triangle
S² = P² + Q²
cosφ = P / S
tanφ = Q / P
φ = arccos(PF)
Units
P — Watts (W) / kW
S — Volt-Amps (VA) / kVA
Q — VAR / kVAR
φ — degrees (°)
⚠ Note: Calculations assume balanced three-phase load and sinusoidal waveform. For unbalanced loads or non-linear loads (harmonics), consult a professional engineer. Power factor is assumed lagging unless specified.
