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.
Kilojoule (kJ)
The kilojoule, symbol kJ, equals 1,000 joules and is used for measuring larger quantities of energy. It was introduced to simplify calculations in nutrition, physics, and engineering, where joules alone would result in very large numbers. Kilojoules are commonly used to express the energy content of foods, fuel consumption, and industrial energy usage. The adoption of the kilojoule has standardized energy measurements across scientific disciplines and commercial applications, offering clarity and ease of use in both everyday and professional contexts.