Enter your voltage (V), current (amps), and phase type to calculate apparent power in kVA. Choose between single-phase and three-phase systems — the calculator applies the correct formula automatically. Results include kVA and optionally estimated kW at a given power factor.
Apparent Power
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Real Power (kW)
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Apparent Power (VA)
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Reactive Power (kVAR)
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kVA stands for kilovolt-amperes and is the unit of apparent power in an electrical system. It represents the total power supplied by the source, combining both the real power (kW) that does useful work and the reactive power (kVAR) that sustains electric and magnetic fields. One kVA equals 1,000 volt-amperes.
kW (kilowatts) measures real power — the actual energy consumed to do work. kVA measures apparent power, which is the total power drawn from the supply. The ratio between them is the power factor (PF). For example, with a power factor of 0.8, a 10 kVA system delivers only 8 kW of real power. In a purely resistive circuit, kVA equals kW (power factor = 1).
For a single-phase system, use the formula: kVA = (Amps × Volts) / 1000. Simply multiply the current in amps by the voltage in volts, then divide by 1,000 to convert from VA to kVA.
For a three-phase system using line-to-line voltage, the formula is: kVA = (√3 × Amps × Volts) / 1000, where √3 ≈ 1.732. This accounts for the three voltage phases that are 120° apart. If you use line-to-neutral voltage instead, multiply by 3 rather than 1.732.
Rearrange the kVA formula to find amps. For single phase: Amps = (kVA × 1000) / Volts. For three phase: Amps = (kVA × 1000) / (√3 × Volts). You need to know either the voltage (to find amps) or the current (to find kVA).
Multiply kVA by the power factor to get kW: kW = kVA × Power Factor. For example, a 50 kVA transformer with a power factor of 0.9 delivers 45 kW of real power. The power factor typically ranges from 0 to 1, and most industrial loads have a power factor between 0.8 and 0.95.
A 500 kVA rating means the equipment can handle up to 500 kilovolt-amperes of apparent power without overheating or being damaged. The actual usable (real) power depends on the connected load's power factor — at 0.8 PF, a 500 kVA unit delivers 400 kW. Always size transformers and generators based on kVA to account for all load types.
Voltage is the electrical potential difference between two points in a circuit, measured in volts (V). It drives current through the load. In kVA calculations, voltage is directly proportional to apparent power — doubling the voltage while keeping current constant doubles the kVA. Common system voltages include 120V, 240V, 480V (single-phase) and 208V, 415V, 480V (three-phase).