About the 3-Phase Power Calculator
What is the 3-Phase Power Calculator?
Industrial and commercial supplies in India are usually 415 V three-phase. This 3-phase power calculator converts between line current and kilowatts using the √3 factor.
Use it to find the power of a running load from a clamp-meter reading, or the current a new machine will draw so you can size cables and breakers.
How to use the 3-Phase Power Calculator
- Find (sample: Power from current)
- Line Voltage (V) (sample: 415)
- Line Current (A) (sample: 20)
- Load (kW) (sample: 10)
- Power Factor (sample: 0.85)
- Press Calculate 3-Phase Power (results also refresh as you type). The result card shows the Result, along with Real power, Apparent power, Reactive power and Line current.
Formula used
P (kW) = √3 × V_L × I_L × PF ÷ 1,000
- I_L from power = P × 1,000 ÷ (√3 × V_L × PF)
- Phase voltage (star) = V_L ÷ √3 (≈ 240 V on a 415 V system)
The formula uses line (phase-to-phase) voltage and line current for both star and delta loads.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Find | Power from current |
| Line Voltage (V) | 415 |
| Line Current (A) | 20 |
| Load (kW) | 10 |
| Power Factor | 0.85 |
| Result | Value |
|---|---|
| Result | 12.22 kW |
| Real power | 12.22 kW |
| Apparent power | 14.376 kVA |
| Reactive power | 7.573 kVAR |
| Line current | 20 A |
| Phase voltage (star) | 239.6 V |
Tips for using the 3-Phase Power Calculator
- Measure all three phases; unbalanced loads draw different currents.
- A 10 kW motor load at 0.85 PF on 415 V draws about 16.4 A per phase.