How is energy measured? It is measured in various units by various industries or countries in much the same way as the value of goods is expressed in Dollars in the U.S. and Yen in Japan and Pounds in Britain.
The table below identifies different units for measuring energy.
| Unit |
Definition |
Used In |
Equivalent to |
| British Thermal Unit BTU |
A unit of energy equal to the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Equivalent to energy found in the tip of a match stick. |
Heating and Cooling industries |
1 BTU = 1055 Joules (J) |
| Calorie or small calorie (calorie) |
The amount of energy needed to raise the temperature of one gram of water by one degree Celsius. |
Science and Engineering |
1 calorie = 0.003969 BTUs |
| Food Calorie, Kilocalorie or large calorie (Cal, kcal, Calorie) |
The amount of energy needed to raise the temperature of one kilogram of water one degree Celsius. The food calorie is often used when measuring the energy content of food. |
Nutrition |
1 Cal = 1000 cal, 4,187 J or 3.969 BTUs |
| Joule (J) |
It is a smaller quantity of energy than calorie and much smaller than a BTU. |
Science and Engineering |
1 Joule = .2388 calories and .0009481 BTUs |
| Kilowatt Hour (kWh) |
An amount of energy from the steady production or consumption of one kilowatt of power for a period of one hour. |
Electrical fields |
1 kWh = 3,413 BTUs or 3,600,000 J |
| Therm |
A unit describing the energy contained in natural gas. |
Home heating appliances |
1 therm = 100,000 BTUs |
