13.365
A
11.111
kVA
10,000
W
1.732051
13.365
A
11.111
kVA
10,000
W
1.732051
The kW to Amps Calculator converts active power (kW) to current (amperes) for both three-phase and single-phase AC electrical systems. This conversion is essential for cable sizing, circuit breaker selection, switchgear rating, and verifying that electrical infrastructure can support a given load.
The relationship between kW and amps depends on both voltage and power factor. For three-phase systems: I = P(kW) × 1000 / (√3 × VL × PF). For single-phase: I = P(kW) × 1000 / (V × PF). Without the power factor, only apparent power (kVA) to current conversion is possible — but cables and protective devices are sized based on actual current regardless of power factor.
This conversion is used daily by electrical engineers and contractors for: cable sizing (NEC Article 310 current-carrying capacity), circuit breaker sizing (NEC 240.6 standard ampere ratings), motor circuit sizing (NEC Article 430 motor full-load current), generator and UPS sizing, and switchboard/panelboard rating verification.
A key insight: for the same kW load, lower power factor means higher current. A 100 kW load at 0.70 PF draws 43% more current than the same load at 1.0 PF. This extra current requires larger cables, higher-rated breakers, and more transformer capacity — all at additional cost. Improving power factor reduces current and thereby reduces infrastructure requirements.
The NEC (National Electrical Code) and IEC 60364 provide tables of standard cable current ratings at various installation conditions. Once you calculate required current in amps, select the cable size from these tables with appropriate derating factors for installation method, grouping, and ambient temperature. Add 25% for motor circuits (NEC 430.22) or 80% continuous loading factor (NEC 210.20) as applicable.
From P = √3 × V_L × I × PF (three-phase): I = P/(√3 × V_L × PF). Converting P to watts: I = (P_kW × 1000)/(√3 × V_L × PF). Single-phase: I = (P_kW × 1000)/(V × PF). kVA = kW/PF — apparent power is larger than active power when PF < 1.
Use the three-phase current result to select cable size and breaker rating for three-phase equipment. Add 25% to continuous loads for breaker sizing (NEC 210.20: breaker must be rated 125% of continuous load current). Use single-phase current for single-phase loads or per-phase calculations. Always use the highest realistic current scenario for safety.
Inputs
Results
41.5A three-phase current. NEC requires circuit rated 125% = 51.8A for continuous operation. Use 60A breaker and 8 AWG copper cable.
Inputs
Results
170A per phase. Per IEC, select 185 mm² cable. Install 200A circuit breaker. Total apparent power demand on transformer: 117.6 kVA.
Current depends on apparent power (kVA), not just active power (kW). kVA = kW/PF. Since I = kVA×1000/(√3×V), you need PF to go from kW to current. Using PF=1.0 underestimates current for inductive loads, leading to undersized cables and breakers — a fire and safety hazard.
Use 0.85 as a conservative assumption for mixed industrial loads. Use 0.80 for motor-dominated loads. Use 0.90 for commercial loads with modern equipment. Use 0.95-1.0 for purely resistive loads (heaters, incandescent lights). When in doubt, use a lower PF to be conservative.
NEC Article 430 provides motor full-load current (FLC) tables that include an efficiency and PF correction factor. For motor circuit sizing, use NEC FLC tables directly rather than calculating from motor nameplate kW. Branch circuit conductors must be rated 125% of FLC; breakers are sized per NEC 430.52 (typically 250% of FLC for inverse-time breakers).
Enter the actual line-to-line voltage. Common voltages: 120V (US single-phase residential), 208V (US three-phase low voltage), 240V (US residential service / single-phase industrial), 277V (US commercial phase-to-neutral), 480V (US industrial), 400V (European 3-phase), 415V (UK/Australia 3-phase), 11kV/33kV (distribution).
For DC: I = P(W) / V(V) — no √3 or power factor needed. A 1000W DC load at 48V draws 1000/48 = 20.83A. For photovoltaic systems and battery banks, DC ampere calculations are straightforward and do not require power factor.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
How helpful was this calculator?
Be the first to rate!
Energy Consumption Calculator
Power & Energy Calculators
Power Factor Correction Calculator
Power & Energy Calculators
BTU / Kilowatt Converter
Power & Energy Calculators
kVA Calculator
Power & Energy Calculators
Power Loss Calculator (Joule Effect)
Power & Energy Calculators
Capacitor Bank Sizing Calculator
Power & Energy Calculators
