What unit is commonly used to state an electric car battery's energy capacity?

An electric car battery’s energy capacity is commonly stated in kilowatt-hours (kWh).

A kilowatt-hour measures energy: one kilowatt delivered for one hour. In an electric vehicle, the figure describes how much electrical energy the battery can store, rather than how quickly it can deliver power. A larger kWh rating generally allows greater range, although weight, aerodynamics, speed, temperature and driving style also matter.

The other choices measure different electrical properties. A volt measures electrical potential, an ampere measures electric current, and an ohm measures resistance. They can all appear in battery specifications, but none is the standard unit for total stored energy.

Battery capacity is often reported as usable and gross capacity. Gross capacity is the pack’s full physical amount, while usable capacity excludes a buffer that helps protect the cells and extend battery life. Charging losses also mean a car may draw more electricity from the grid than the battery actually stores.