Although energy can exist in many different forms, it can be measured and compared along a single axis because it can be converted between forms. Measurement of the familiar forms of energy involves measuring quantities of mechanical force, weight, distance, temperature, electric charge and current, and/or time.
|SI* unit of energy||joule||Force of 1 newton over distance of 1 meter;
|Commonly unit of electrical energy||kWh (kilowatt hour)||Power of 1,000 watts for 1 hour||3,600,000||1||3,413|
|Common English units of thermal energy or fuel equivalents||BTU (British Thermal Unit)||Temperature increase of 1 degree Fahrenheit in 1 pound of water at 1 atmosphere||1,055||2.931*10-4||1|
|CCF (Hundred Cubic Feet)||1 hundred cubic feet of natural gas at standard pressure||103,100|
|GGE (Gasoline Gallon Equivalent)||Energy content of 1 liquid gallon of gasoline||1.2*108||33.4||114,113|
|Other units of energy||erg||Force of 1 dyne over distance of 1 centimeter||10-7|
|(kilogram) calorie||Temperature increase of 1 degree Celseus in 1 kilogram of water at 1 atmosphere||4.19|
* The International System of Units (SI) is the modern form of the metric system and has units of measurement defined in terms of seven base units and numerous derived units. Accordingly, the Joule is a derived unit defined in terms of the base units of force (newton) and distance (meter).