Power Converter

Power is the rate at which energy is transferred, used, or produced. The SI unit is the watt, equal to one joule per second. Converting power units does not change the underlying rate; it expresses that rate on a scale suited to a device, engine, heating system, or power plant. This converter uses watts as a common base and supports watts, kilowatts, megawatts, mechanical horsepower, British thermal units per hour, and foot-pounds per second. Metric power units differ by powers of one thousand. One kilowatt equals 1,000 watts, and one megawatt equals 1,000,000 watts. A 2.5-kilowatt appliance therefore has a rated power of 2,500 watts. Metric prefixes make it easy to compare small electronics, household equipment, industrial machinery, and utility-scale generation without unwieldy numbers. Mechanical horsepower is widely used for engines and motors. One mechanical horsepower equals approximately 745.69987158 watts. Horsepower has several definitions, including metric, electrical, and boiler horsepower, so the label matters. This calculator specifically uses mechanical horsepower. Manufacturer ratings may describe peak output, continuous output, shaft power, or input power, which are not interchangeable even when they use the same unit. BTU per hour is common in heating, ventilation, and air-conditioning. One BTU per hour equals approximately 0.29307107 watt. A 12,000-BTU-per-hour air conditioner therefore represents about 3,516.85 watts of thermal transfer capacity. That number is not necessarily its electrical consumption. Efficiency measures such as COP, EER, or SEER connect heating or cooling output to the electricity required. Foot-pounds per second express a rate of mechanical work in US customary units. One foot-pound per second equals approximately 1.35581795 watts. Because one mechanical horsepower is defined as 550 foot-pounds per second, the two factors are consistent. Do not confuse foot-pound force, a unit of work or torque depending on context, with foot-pounds per second, which explicitly describes power. Power and energy are related but distinct. A watt is a rate, while a watt-hour is an amount of energy accumulated over time. A 1,000-watt heater running for two hours uses 2 kilowatt-hours of energy. Converting watts to kilowatt-hours requires a duration, so a power converter alone cannot calculate an electricity bill. Similarly, engine power does not by itself determine fuel consumption, speed, or delivered work because efficiency and operating time also matter. Real equipment ratings often include rounding and tolerances. The calculator preserves useful decimal precision, but the source specification determines the true accuracy. Use nameplate data, applicable standards, and consistent definitions for engineering decisions. For everyday comparisons and preliminary estimates, select the starting unit, target unit, and value to obtain an immediate equivalent.