Enter any two known values — Voltage (V), Current (I), Resistance (R), or Power Factor (PF) — and the Electrical Power Calculator solves for Power (P) along with any remaining unknowns, with support for both AC and DC circuit types.
Power
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Electrical power is the rate at which electrical energy is transferred by an electric circuit. It's measured in watts (W) and represents how much energy is consumed or produced per unit time.
For DC circuits: P = V × I = V²/R = I²×R. For AC circuits: P = V × I × cos(φ), where φ is the phase angle and cos(φ) is the power factor.
Power factor is the ratio of real power to apparent power in AC circuits, ranging from 0 to 1. It represents how efficiently electrical power is being used. A power factor of 1 indicates maximum efficiency.
Power dissipated by a resistor can be calculated using P = I²×R, P = V²/R, or P = V×I, where P is power in watts, I is current in amperes, V is voltage in volts, and R is resistance in ohms.
Using the formula P = V × I, the power would be 120 V × 10 A = 1,200 watts or 1.2 kilowatts. This assumes a DC circuit or AC circuit with unity power factor.
DC power calculations use P = V × I directly. AC power calculations include the power factor: P = V × I × cos(φ). The power factor accounts for the phase difference between voltage and current in AC circuits.
You need at least two electrical parameters (voltage, current, resistance, or power) to calculate the missing values using Ohm's law and power formulas. The calculator will compute all other values automatically.