Electric Power Calculator — P=VI

Electric power is the rate at which electrical energy is transferred or consumed. Measured in watts (W), it is determined by the product of voltage and current, or equivalently by current squared times resistance. Understanding power relationships is fundamental to circuit design, electrical safety, energy efficiency, and cost analysis.

The three power formulas (P=VI, P=I²R, P=V²/R) are all derived from Ohm's law and are interchangeable depending on which quantities are known. In practice, knowing any two of voltage, current, and resistance lets you calculate the third via Ohm's law, and then power from any of the three formulas.

Energy consumption — measured in kilowatt-hours (kWh) — is power multiplied by time. Understanding this relationship helps households reduce electricity bills by identifying high-consumption appliances, sizing solar panel systems, and evaluating efficiency upgrades. This calculator is useful for students learning circuit theory and for practical household energy audits.