Three-Phase Current Calculator
Estimate line current in a balanced three-phase system from power, line-to-line voltage, power factor and overall efficiency.
How to use this calculator
- Enter output power, line-to-line voltage, power factor and efficiency as a percentage.
- Check that all inputs use the same units, time period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by three phase current calculator calculator
I ≈ Pout × 1000 ÷ (√3 × VLL × power factor × efficiency).
- I ≈ Pout × 1000 ÷ (√3 × VLL × power factor × efficiency).
- This is a simplified balanced-load estimate, not a cable, fuse or protection-device sizing approval. Use nameplate data, applicable electrical codes and qualified engineering review.
- The tool validates entered values and formats results for readability; it does not verify assumptions against external records.
Worked examples
Worked example
15 kW output, 400 V, power factor 0.86 and efficiency 92%.
15,000 ÷ (√3 × 400 × 0.86 × 0.92) ≈ 27.3 A.
Estimated balanced line current is about 27.3 A under the entered assumptions.
Understanding the result
Estimate line current in a balanced three-phase system from power, line-to-line voltage, power factor and overall efficiency.
This is a simplified balanced-load estimate, not a cable, fuse or protection-device sizing approval. Use nameplate data, applicable electrical codes and qualified engineering review.
Important notes
This is a simplified balanced-load estimate, not a cable, fuse or protection-device sizing approval. Use nameplate data, applicable electrical codes and qualified engineering review.
Treat the result as an estimate based on the entered inputs. For regulated, engineering, employment, tax or business decisions, check applicable official rules, specifications and professional guidance.
Frequently asked questions
Does this apply to single-phase systems?
No. This formula assumes a balanced three-phase system.
Can this size a cable or breaker?
No. Current is only one input; installation method, temperature, fault current, protection and local code also matter.
How should I use the result?
This is a simplified balanced-load estimate, not a cable, fuse or protection-device sizing approval. Use nameplate data, applicable electrical codes and qualified engineering review.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.