Power distribution

Load Current & Power Calculator (kW · kVA · A)

Convert between active power (kW), apparent power (kVA), and current (A) for DC, single-phase, and balanced three-phase loads. A fast starting point for sizing breakers, contactors, ATS, CTs, and cables.

System

Known value

Voltage (V)

Power factor

ⓘPower factor is used for AC only. For DC it is treated as 1 and kW = kVA.

Current

— A

Active power

— kW

Apparent power

— kVA

Formulas used

Three-phase: I = S / (√3 × V) S(kVA) = √3 × V × I / 1000 P = S × cos φ Single-phase: I = S / V S(kVA) = V × I / 1000 DC: I = P / V (cos φ = 1, kW = kVA)

where I is line current (A), V is voltage (V), S is apparent power (kVA), P is active power (kW), and cos φ is power factor. Enter any one of kW, kVA, or A, and the calculator returns the other two.

Frequently asked questions

What is the difference between kW and kVA?

kW is the active (real) power that does work; kVA is the apparent power the circuit must carry. They are related by the power factor: kW = kVA × cos φ. Cables, breakers, and transformers are sized on kVA / current, not kW alone.

Which voltage do I enter for three-phase?

The line-to-line voltage (for example 400 V), because the √3 formula uses the line voltage.

Size the device next

With the current known, size the breaker, contactor, or transfer switch — or ask JUTRION for a suitable product for your market.

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Standards referencedIEC 60038 (standard voltages) · basic three-phase power relationships (P = √3 · V · I · cos φ).

Engineering estimate for guidance only. Final sizing must account for the actual load, diversity, harmonics, and the applicable installation rules, verified by a qualified person.