Formula Used
For balanced three phase power, the main formula is:
kW = √3 × VLL × A × PF ÷ 1000
When efficiency is included, the calculator also applies:
Useful kW = kW × Efficiency ÷ 100
Demand and margin are then applied to support planning:
Final kW = Useful kW × Demand Factor × Systems × Safety Margin
If line to neutral voltage is entered, it is converted first:
VLL = VLN × √3
How to Use This Calculator
- Enter the measured or rated current in amps.
- Enter the three phase voltage value.
- Select line to line or line to neutral voltage.
- Enter the power factor of the load.
- Add efficiency when motor output power matters.
- Use demand factor for expected operating load.
- Add safety margin for design allowance.
- Press the calculate button to see the result.
- Download the result as CSV or PDF when needed.
Example Data Table
| Load |
Amps |
Voltage |
Power Factor |
Efficiency |
Approx. kW |
| Small motor |
25 A |
400 V |
0.82 |
92% |
13.06 kW |
| Workshop feeder |
80 A |
415 V |
0.88 |
96% |
50.59 kW |
| Industrial panel |
150 A |
480 V |
0.90 |
97% |
108.89 kW |
Three Phase Power Conversion Guide
A three phase amps to kW calculator helps convert current into real power. It is useful for motors, feeders, panels, pumps, compressors, and industrial machines. Three phase systems carry power through three alternating conductors. This makes delivery smoother than single phase power. It also reduces conductor size for many loads.
Why Power Factor Matters
Current alone does not show real working power. Voltage and power factor must also be known. Power factor shows how effectively current becomes useful work. A power factor of one is ideal. Motors often run lower than one. Inductive loads may have delayed current. That delay reduces real kilowatts.
Voltage Selection
Line to line voltage is normally used for three phase calculations. Some users may only know line to neutral voltage. This calculator can convert that value into line voltage. The conversion uses the square root of three. This helps keep the result consistent.
Efficiency and Demand
Efficiency is important for motors and driven equipment. Input power is not always equal to shaft output power. Losses appear as heat, friction, and magnetic losses. Demand factor helps model actual operating load. A machine may not always run at full rated current. This factor can make estimates more realistic.
Safety Margin
Design work should include margin. Margin helps with temperature, future expansion, voltage variation, and measurement tolerance. It should not replace electrical codes or engineering review. It gives a planning buffer before equipment is selected.
Best Use Cases
Use this tool for early sizing, comparison, and quick reporting. It can help estimate generator load, feeder demand, and motor power. Always verify final designs with local standards. Also check cable rating, breaker rating, starting current, and duty cycle.
FAQs
1. What is a three phase amps to kW calculator?
It converts three phase current into kilowatts. It uses amps, voltage, and power factor. This version also supports efficiency, demand factor, system count, and safety margin.
2. Which voltage should I enter?
Enter line to line voltage when available. It is the common value for three phase power calculations. If you only know line to neutral voltage, select that option.
3. Why is power factor required?
Power factor converts apparent power into real power. Motors and inductive loads often have lower values. Without power factor, the kW result may be too high.
4. What is a good power factor value?
Many motors operate between 0.75 and 0.95. Resistive loads are close to 1. Use the equipment nameplate or measured value for better accuracy.
5. Does efficiency change the main kW result?
Yes. Efficiency adjusts input power into useful output power. This is helpful for motors, pumps, and machines where output power matters.
6. What does demand factor mean?
Demand factor estimates expected operating load. A 100 percent value means full load. A lower value can model equipment that rarely runs at full capacity.
7. Why add a safety margin?
A safety margin adds planning allowance. It can help cover voltage changes, future load growth, heat, and measurement tolerance. Final designs still need code review.
8. Can I download the results?
Yes. After calculation, use the CSV button for spreadsheet data. Use the PDF button for a clean printable report.