When converting energy, the units of energy must be considered to solve relevant equations.

There are two major types of energy units: basic, or common, energy units and source-based energy units.

When discussing common or basic energy units, the standard measurements include the following:

### Joule

The joule is the basic energy unit of the metric system. It is defined using meters, kilograms, and seconds.

**Calorie**

A **calorie** was first defined in terms of heating water.

The traditional definition of a calorie is measured by the amount of heat required to raise the temperature of 1 gram of water by 1 degree C.

### British Thermal Unit

This is the British system analog of a calorie and is included when converting one caloric measurement to another.

### Kilowatt-Hour (kWh)

A **kilowatt**-hour is a standard unit of electricity production and consumption

### Large Scale Units

It's common to use large-scale units based on the joule, Btu, and kWh when referencing national or global energy budgets.