Calculate three-phase electrical power. Enter voltage, current, and power factor to find watts, kW, and kVA for balanced three-phase circuits.
Three-phase power is the standard for commercial, industrial, and large residential electrical systems worldwide. It provides a more efficient way to transmit electrical power by using three conductors carrying alternating currents that are 120 degrees out of phase with each other. This results in constant power delivery, unlike single-phase which fluctuates.
Three-phase systems deliver √3 (1.732) times more power than single-phase using only 1.5 times the conductors. Most commercial buildings, factories, large HVAC systems, and electric vehicle fast chargers use three-phase power. The standard voltages are 208V, 240V, 480V, and 600V in North America, and 380V/400V in many other countries.
This calculator computes the real power (kW), apparent power (kVA), and current for balanced three-phase systems. Enter any two values plus power factor to find the others. It's essential for electrical panel sizing, motor selection, and load calculations.
Understanding this metric in precise terms allows energy managers to evaluate investment options, forecast savings, and build compelling business cases for efficiency upgrades and retrofits.
Three-phase power calculations are fundamental for commercial and industrial electrical design. This calculator handles the √3 factor and power factor to provide accurate kW, kVA, and current values for circuit design and load planning. Consistent measurement creates a reliable baseline for tracking energy efficiency improvements and validating the impact of conservation measures and equipment upgrades over time.
P (W) = √3 × V_line × I_line × PF
Result: 35.3 kW
P = √3 × 480 × 50 × 0.85 = 1.732 × 480 × 50 × 0.85 = 35,334 W = 35.3 kW. Apparent power: √3 × 480 × 50 = 41.6 kVA.
Wye (Star): Has a neutral conductor. Provides two voltages (e.g., 480V line-to-line and 277V line-to-neutral). Most common in commercial buildings. Delta: No neutral conductor. Provides one voltage (line-to-line). Common in industrial motor applications.
Real power (kW), reactive power (kVAR), and apparent power (kVA) form a right triangle. kVA = √(kW² + kVAR²). Power factor = kW / kVA = cos(φ). Improving power factor reduces apparent power and current for the same real power output.
Large motors (5+ HP), commercial HVAC systems, industrial machinery, welding equipment, DC fast chargers for EVs, and data center power distribution all use three-phase power for efficiency and the ability to deliver high power through smaller conductors.
The √3 (1.732) factor arises from the 120-degree phase angle between the three phases. It accounts for the vector sum of the three-phase currents. It applies when using line-to-line voltage in the power formula.
kW is real power (doing useful work). kVA is apparent power (total power drawn, including reactive component). kW = kVA × power factor. Generators and transformers are rated in kVA because they must supply the full apparent power.
I = kW × 1,000 / (√3 × V × PF). For example, a 30 kW load at 480V and 0.85 PF draws: 30,000 / (1.732 × 480 × 0.85) = 42.5 amps per phase.
In North America: 208V/120V (wye), 240V (delta), 480V/277V (wye), and 600V. Internationally: 380V, 400V, 415V, and 440V are common. The voltage depends on the transformer configuration and local standards.
A balanced load draws equal current on all three phases. Motors are inherently balanced. When single-phase loads (lighting, outlets) are distributed across phases, the goal is to balance them as evenly as possible to minimize neutral current.
Use single-phase for loads connected between one phase and neutral (120V or 277V outlets, small equipment). Use three-phase for loads connected across all three phases (motors, large HVAC, three-phase panels). The formulas are different.