Line Current Calculator: Single & Three-Phase Amps

line current calculator

Convert power, phase current or voltage into line current for DC, single-phase and three-phase (wye/delta) systems. Includes formulas, examples, and FAQs.

three-phase line current; delta line current

Line current is the current in each supply conductor. For balanced 3-phase, \(I_L=P/(\sqrt{3}V_{LL}PF)\). In delta \(I_L=\sqrt{3}I_{phase}\); in wye \(I_L=I_{phase}\).

Formula & Table Summary:

 DC / 1-phase: I = P / (V · PF) 3-phase (balanced): I_L = P / (√3 · V_LL · PF) Apparent power: I (1Φ) = S / V I_L (3Φ) = S / (√3 · V_LL) Delta/Wye: Wye: I_L = I_phase Delta: I_L = √3 · I_phase

Inputs: P (W or kW), S (VA or kVA), V (V), V_LL (V), PF (0–1), I_phase (A). Output: I_L (A).

amps from kW calculator

Determine line current (A) with phase current and phase voltage, or convert power (kW/kVA) and phase current or phase voltage to line current (A) on DC, single-phase and three-phase (wye/delta). Enter AC real power in PF.Phase voltages may also be entered and conversion shown step-by-step in typical cases (kW to A, kVA to A, phase to line). Apply it in checking the panel design, conductor sizing a test, and rapid verification of the load. When sizing breakers or conductors, remember to use power factor of AC loads, and to use code derating of continuous loads in the calculation.

balanced 3-phase current calc

Type	Input	Values	Formula Used	I_L (A)
DC	P,V	1200 W, 48 V	I=P/V	25.00
1-phase AC	P,V,PF	2300 W, 230 V, 0.8	I=P/(V·PF)	12.50
3-phase (wye)	P,V_LL,PF	10 kW, 400 V, 0.9	I_L=P/(√3·V_LL·PF)	16.04
3-phase (delta given I_phase)	I_phase	I_phase=30 A	I_L=√3·I_phase	51.96
3-phase (from S)	S,V_LL	50 kVA, 11 kV	I_L=S/(√3·V_LL)	2.63

Frequently Asked Questions - line current calculator:

What is line current?

Line current is the current in a supply conductor of a multi-phase system; it’s the current you measure in each line conductor.

How do I calculate line current from power for 3-phase?

For balanced 3-phase: I_L = P / (√3 · V_LL · PF). Use S for apparent power: I_L = S / (√3 · V_LL).

How to get line current from phase current in delta and wye?

Wye (star): I_L = I_phase. Delta: I_L = √3 · I_phase.

What voltage should I use for three-phase formulas?

Use line-to-line voltage V_LL for the standard three-phase power formulas. For wye phase calculations use V_LN accordingly.

How to convert kW to amps?

Convert kW to W (×1000) then use I = P/(V·PF) for single-phase or the three-phase formula for 3Φ.

Do I need power factor?

Yes for real power (kW). If you only have VA (apparent power), PF is not needed; use S instead of P.

Can line current exceed phase current?

Depends on connection: in delta line current = √3·I_phase so it can be larger; in wye they are equal.

How accurate is the balanced 3-phase formula?

It’s exact for balanced sinusoidal systems. For unbalanced loads, compute each phase or measure with clamp meters.

Does frequency affect these formulas?

No—frequency doesn’t appear in the steady-state power/current algebraic formulas, but it affects impedance and transients in real systems.

How do I size breakers from line current?

Select a breaker rating above the continuous calculated current and apply code derating (e.g., 125% for continuous loads). Always follow local electrical codes.

Tags: line current calculator line current formula three-phase line current delta line current wye line current IL from P calculator amps from kW calculator phase to line current balanced 3-phase current calc line current converter