Energy Unit Definitions
Our Energy Converter helps you convert between joules, kilowatt-hours, calories, BTUs, and electron volts. Perfect for engineers, scientists, and homeowners, this tool provides accurate energy conversions for electricity bills, food calories, physics calculations, and power consumption analysis.
Joule (J)
The joule is the SI derived unit of energy, named after the English physicist James Prescott Joule. It is defined as the work done by a force of one newton acting over a distance of one meter.
Kilocalorie (kcal)
A kilocalorie (often called a "calorie" in nutrition) equals 1,000 calories or approximately 4,184 joules. It is commonly used to measure food energy content.
Kilowatt-Hour (kWh)
A kilowatt-hour is a unit of energy equivalent to one kilowatt of power sustained for one hour. It is commonly used for measuring electrical energy consumption. One kWh equals 3,600,000 joules.
British Thermal Unit (BTU)
A BTU is the amount of energy required to heat one pound of water by one degree Fahrenheit. It is commonly used in heating and cooling systems. One BTU equals approximately 1,055 joules.
Foot-Pound (ft·lb)
A foot-pound is a unit of energy representing the work done by a force of one pound acting through a distance of one foot. It is commonly used in mechanical engineering, particularly in the United States and United Kingdom for measuring torque and energy in rotating systems.
Frequently Asked Questions on Energy Conversion
Q: How to convert calories to joules?
Multiply calories by 4.184. Example: 100 calories = 418.4 joules. 1 Calorie (kcal) = 4,184 joules.
Q: How many BTUs are in a kWh?
1 kilowatt-hour equals 3,412.14 BTUs. This is equivalent to 3.6 million joules.
Q: What is the energy in a calorie?
1 calorie (small c) = 4.184 joules. 1 Calorie (large C, kcal) = 1,000 calories = 4,184 joules, the energy to heat 1 kg of water by 1°C.
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