In which unit is electrical energy commonly measured?

Electrical energy is commonly measured in kilowatt-hours. This unit represents the amount of energy consumed when a device rated at one kilowatt operates for one hour. It's particularly useful for billing purposes in residential and commercial electricity usage, as it relates directly to how much energy is drawn from the power grid over time.

While joules are indeed a unit of energy, and can be used to quantify electrical energy, they are not typically used in the context of household or industrial electricity billing, where kilowatt-hours are more relevant and practical. Watts measure power, which is the rate at which energy is used or generated, rather than the total consumption over time. Amperes refer specifically to the flow of electric current, not energy itself. Therefore, kilowatt-hours is the most appropriate unit for measuring electrical energy in common contexts.