Electric Power Calculator

Electric power is the rate at which electrical energy is transferred or consumed, calculated as P = V × I (voltage times current). Measured in Watts (W), where 1 Watt equals 1 Joule per second. A 60W light bulb consumes 60 Joules of electrical energy every second.

Combining P = VI with Ohm's Law (V = IR) gives P = I²R or P = V²/R. These formulas let you calculate power knowing different combinations of voltage, current, and resistance. Very useful for circuit design and analysis.

Watts (W) measure power - the rate of energy use. Kilowatt-hours (kWh) measure total energy consumed over time. A 1000W (1kW) heater running for 2 hours uses 2 kWh. Your electric bill charges per kWh, not per watt.

Power ratings show maximum power consumption. A 1500W hair dryer uses 1.5 kW when running. Knowing power helps calculate energy costs, size electrical systems, and avoid overloading circuits. Most home circuits handle 15-20 Amps at 120V (1800-2400W).

Power is lost as heat (P = I²R) when current flows through wire resistance. Higher current causes more loss (squared relationship). This is why high-voltage transmission lines use high voltage and low current to minimize power loss over long distances.

Calculate energy in kWh: (Power in kW) × (Hours used). Multiply by your rate ($/kWh). Example: 100W bulb for 30 hours = 0.1kW × 30h = 3 kWh. At $0.12/kWh, that's $0.36. LED bulbs use less power, saving money.