How is electrical energy commonly measured?

Electrical energy is commonly measured in kilowatt-hours (kWh) because this unit represents the amount of energy consumed when a power of one kilowatt is used for one hour. This measurement is particularly relevant for billing purposes by utility companies, as it reflects the total energy usage over time. The concept of kilowatt-hours helps in understanding how much electrical energy is being drawn from the grid and enables consumers to track their energy consumption in a practical context.

While watts express the rate of energy transfer or power at a specific moment and volts indicate the electrical potential difference, neither directly measures total energy consumed over time. Amperes measure the flow of electric current but do not account for the voltage, and thus cannot be used to calculate energy consumption without additional information. Kilowatt-hours, therefore, provide a comprehensive and user-friendly way to quantify energy usage.