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