Metric Republic / Electrical engineering / Electrical Load Current Calculator

Electrical Load Current Calculator

Calculate single- or three-phase current from real power, voltage, power factor and efficiency.

Updated September 2026

How it works

Calculate single- or three-phase current from real power, voltage, power factor and efficiency.

Formula:
I1φ = P/(V·PF·η); I3φ = P/(√3·V·PF·η).

Before you use the result: Calculated load current is not a cable ampacity selection; apply installation and protection rules separately.

Practical use

Use verified material data and project geometry. Treat results as planning estimates and compare them with the energy/thermal requirements that apply to the project.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

How to use this calculator: Electrical Load Current Calculator

Calculate single- or three-phase current from real power, voltage, power factor and efficiency.

Quick workflow

Enter the project values from the latest drawing, specification or verified site measurement.
Check units, material properties, allowances and any code- or supplier-specific parameters before calculating.
Review the result together with the formula, assumptions and the related checks shown on this page.

Worked example

Example inputs: System: Three phase; Real load power [kW]: 15; Line voltage [V]: 400; Power factor cosφ: 0.9.

Using the sample values built into the calculator, the calculation gives approximately: Load current: 26.15 A; Apparent power: 18.12 kVA.

What the result means

Calculation method: I1φ = P/(V·PF·η); I3φ = P/(√3·V·PF·η).

Before using the result: Calculated load current is not a cable ampacity selection; apply installation and protection rules separately.

Common questions

What does this calculator do?

Calculate single- or three-phase current from real power, voltage, power factor and efficiency.

Which inputs should I verify?

Key inputs to verify include: System, Real load power [kW], Line voltage [V], Power factor cosφ.

Can I use this result for final design or ordering?

Use the result as a transparent planning or checking aid. Final design, code compliance, supplier selection and project-specific decisions still need to be verified where applicable. Calculated load current is not a cable ampacity selection; apply installation and protection rules separately.

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