What is the SI unit for measuring energy?

The SI unit for measuring energy is the joule (J). This unit is defined as the amount of energy transferred when a force of one newton acts through a distance of one meter. Therefore, the joule provides a standard measure of energy that is used universally in scientific contexts.

In contrast, other units listed such as kilowatt, calorie, and watt serve different purposes. The kilowatt is a unit of power, typically used to quantify the rate of energy transfer or consumption. The calorie, while historically significant and still used in dietary contexts, is not an SI unit; it is specifically defined as the amount of energy needed to raise the temperature of one gram of water by one degree Celsius. The watt, meanwhile, is also a unit of power, equating to one joule per second. This further clarifies that while these other units are related to energy, they do not serve as the standard SI unit for measuring energy itself.