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Convert Joule to Kilocalorie (th)

Please provide values below to convert joule [J] to kilocalorie (th) [kcal (th)], or vice versa.



Definition: A joule (symbol: J) is a derived unit of energy in the International System of Units (SI). It is defined as the energy transferred to an object when a one newton force is applied to the object in the direction of its motion through a distance of one meter. It is also defined as the energy dissipated as heat when a 1 ampere electric current passes through a resistance of one ohm in the course of one second. It has a number of representations both in SI base units as well as other SI units such that:

J = kg·m2/s2 = N·m = Pa·m3 = W·s = C·V

History/origin: The unit, joule, is named after James Prescott Joule, an English physicist and mathematician who helped develop the Kelvin scale. He also discovered the relationship between heat and mechanical work, leading to the law of conservation of energy, and subsequently, the first law of thermodynamics.

Current use: As an SI derived unit, the joule is used within a variety of scientific contexts. Practical examples of energy measurement using joules include the energy required to lift objects, the energy released when objects fall, the heat required to raise temperature, and the kinetic energy of moving objects.

One of the dimensional representations of a joule is the N·m (Newton-meter), which is equivalent to the SI unit for torque. These units however, are different, and should be considered as such. Even though the joule is algebraically equal to the N·m, the N·m should not be used to represent the joule whenever possible, to avoid confusion with torque.


Definition: A kilocalorie (symbol: kcal or Cal) is a unit of energy defined based on the calorie and is equal to 1000 calories or 4.1868 kilojoules. A calorie (small calorie) is defined as the amount of energy required to increase the temperature of one gram of water by one °C. Kilocalories are also referred to as large calories or food calories, and are sometimes referred to as Calories, which can be ambiguous, and mistaken for the small calorie.

History/origin: The kilocalorie shares its origin with the small calorie except that it is defined in terms of the kilogram rather than the gram. The term is based on the Latin "calor," meaning heat, and the calorie was first defined as a unit of heat energy in 1824 by Nicolas Clement. The kilocalorie however, was not introduced to the American public until 1887, by Wilbur Olin Atwater.

Current use: Although the kilocalorie is generally considered an obsolete unit, it is still widely used alongside the SI unit of kilojoule to measure food energy. In countries where SI has not been adopted, such as the US, kilocalories, typically referred to as simply "Calories," are still the preferred measurement of food energy. Kilocalories are also sometimes seen in chemistry.

The kilo prefix is based on the SI prefixes, but calories with prefixes beyond the multiple of kilo are not commonly used.

Joule to Kilocalorie (th) Conversion Table

Joule [J]Kilocalorie (th) [kcal (th)]
0.01 J2.3900573613767E-6 kcal (th)
0.1 J2.39006E-5 kcal (th)
1 J0.0002390057 kcal (th)
2 J0.0004780115 kcal (th)
3 J0.0007170172 kcal (th)
5 J0.0011950287 kcal (th)
10 J0.0023900574 kcal (th)
20 J0.0047801147 kcal (th)
50 J0.0119502868 kcal (th)
100 J0.0239005736 kcal (th)
1000 J0.2390057361 kcal (th)

How to Convert Joule to Kilocalorie (th)

1 J = 0.0002390057 kcal (th)
1 kcal (th) = 4184 J

Example: convert 15 J to kcal (th):
15 J = 15 × 0.0002390057 kcal (th) = 0.003585086 kcal (th)

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