kWh

Kilowatt-hour (symbol kWh) is a unit of electrical energy commonly used to measure the energy consumption of electrical devices. It represents the amount of energy consumed when a device with a power of one kilowatt operates for one hour.

One kilowatt equals 1000 watts and one hour equals 3600 seconds, so 1 kWh equals 3,600,000 joules, or 3.6 megajoules (3,600 kilojoules). It is a unit of energy, not power. For example, a 100-watt light bulb left on for 10 hours consumes 1 kWh: 100 W × 10 h = 1000 Wh = 1 kWh.

Usage and context: The kilowatt-hour is widely used by electric utilities for billing and by consumers to describe energy usage over a period. The official SI unit of energy is the joule, and the kilowatt-hour is a non-SI unit accepted for use with the SI.

Multiples and related units include the megawatt-hour (MWh) and gigawatt-hour (GWh). In practice, kWh is the standard measure for household electricity consumption and is commonly cited in energy bills, energy meters, and consumer energy labels.