The watt (W) is the SI base unit of power, defined as one joule per second, measuring the rate of energy transfer. From light bulb brightness ratings to phone charger output, the watt appears in everyday product specifications worldwide. One watt equals exactly 1 joule per second, or about 0.001341 horsepower.

The megawatt (MW) equals one million watts, used to express the output of power plants, large industrial facilities, and data centers. A typical wind turbine generates 2–3 MW, while a large coal plant may produce 500–1,000 MW. One megawatt can power roughly 800–1,000 homes simultaneously.