Enter your Phase Type (single or three-phase), Current (amps), and Voltage (volts) to calculate your circuit's Apparent Power in kVA — plus see the exact formula used so you know what's happening under the hood.
Apparent Power
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Formula Used
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Single-phase uses the formula kVA = (Amps × Volts) / 1000, while three-phase uses kVA = (√3 × Amps × Volts) / 1000. Three-phase systems include the square root of 3 (1.732) multiplier to account for the phase relationships.
kVA (kilovolt-amperes) is apparent power, which combines both real power and reactive power. kW (kilowatts) is real power only. kVA represents the total power flowing in a circuit, while kW is the actual power consumed to do work.
Amps (amperes) measure electric current - the flow of electrical charge through a circuit. One amp equals one coulomb of charge flowing past a point in one second.
Voltage is the electric potential difference between two points, measured in volts (V). It represents the electrical pressure that drives current through a circuit.
For three-phase systems, line-to-line voltage is measured between any two phases, while line-to-neutral is measured between a phase and neutral. Both formulas give the same kVA result when used correctly.
A transformer changes voltage levels in electrical systems. Transformers are rated in kVA because this represents their total capacity to handle apparent power, regardless of the power factor of the connected load.
We divide by 1000 to convert from volt-amperes (VA) to kilovolt-amperes (kVA). The prefix 'kilo' means thousand, so 1 kVA = 1000 VA.
This calculator is designed for AC systems. For DC systems, you would calculate power in kilowatts (kW) using P = V × I / 1000, as there is no reactive power component in DC circuits.