Kilowatt Hour (kWh)
The kilowatt-hour, symbolized as kWh, is a common unit in electricity billing and energy reporting. It is the energy used by a 1-kilowatt device for 1 hour, or 3.6 million joules. With the advent of electrification in the late 1800s and early 1900s, the kilowatt-hour made measuring electrical energy simpler for both utilities and customers. Its use is crucial for billing, energy management, and understanding electricity use in homes, industry, and renewable energy.
Watt Hour (Wh)
The watt-hour, symbolized as Wh, represents the energy consumed when one watt of power is used for one hour, equivalent to 3,600 joules. Introduced with the spread of electrical systems in the late 19th century, the watt-hour is a practical unit for measuring smaller-scale electrical consumption, such as that of batteries and small devices. It is widely used in electronics, computing, and renewable energy storage. While large-scale power use is measured in kilowatt hours, watt-hours provide fine-grained detail for portable and household applications.