Enter the 3-phase load real power in kilowatts.
Use 100% if efficiency losses are unknown or already included in power.
Formula used:
I = P / (√3 × VL × PF × η)
What this 3 phase current calculator does
This calculator estimates line current for a balanced three-phase electrical system. It supports two common input methods:
- Real power (kW) with power factor and efficiency, often used for motors and industrial loads.
- Apparent power (kVA), often used when transformer or equipment kVA rating is known.
The result is shown in amps (A), with an optional phase-current interpretation for wye or delta connections.
Three-phase current formulas
1) From real power (kW)
For balanced three-phase systems:
I = P / (√3 × VL × PF × η)
- I = line current (A)
- P = real power (W)
- VL = line-to-line voltage (V)
- PF = power factor
- η = efficiency (decimal form)
2) From apparent power (kVA)
I = S / (√3 × VL)
- S = apparent power (VA)
How to use the calculator
- Select calculation mode: kW or kVA.
- Enter the power value and line voltage.
- If in kW mode, enter power factor and efficiency.
- Choose wye or delta if you want a phase-current interpretation.
- Click Calculate Current.
Quick reference table
| System | Relationship |
|---|---|
| Wye (Star) | Line current = Phase current |
| Delta | Line current = √3 × Phase current |
| Balanced 3-phase power | P = √3 × VL × I × PF × η |
Common mistakes to avoid
- Using phase voltage instead of line-to-line voltage in the 3-phase formula.
- Entering power factor as a percentage instead of decimal (use 0.9, not 90).
- Forgetting to include efficiency when input power is mechanical output (such as motor shaft power).
- Mixing single-phase and three-phase equations.
Practical note
This tool is intended for estimation. For final conductor sizing, protection settings, and compliance, always follow local electrical codes and consult a qualified electrician or electrical engineer.