Home / Energy Conversion / Convert kJ to J

Convert kJ to J

Please provide values below to convert kilojoule [kJ] to joule [J], or vice versa.



Definition: The kilojoule is an SI (International System of Units) derived unit of energy that is equal to 1000 joules. The joule is defined as the amount of energy transferred to an object when a one newton force acts on an object in the direction movement through a distance of one meter.

History/origin: The kilojoule, like other SI derived units, uses SI prefixes to denote multiples or submultiples of the given unit. In this case, the prefix "kilo" is used to express a multiple of 1000.

Current use: In countries that have adopted SI, the kilojoule is widely used as a unit of food energy. In some cases, both kilojoules and kilocalories are displayed, though in countries such as the United States, only kilocalories are shown (often referred to as "Calories") on food labels. Aside from this everyday use, kilojoules are used within scientific contexts around the world.


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.

Kilojoule to Joule Conversion Table

Kilojoule [kJ]Joule [J]
0.01 kJ10 J
0.1 kJ100 J
1 kJ1000 J
2 kJ2000 J
3 kJ3000 J
5 kJ5000 J
10 kJ10000 J
20 kJ20000 J
50 kJ50000 J
100 kJ100000 J
1000 kJ1000000 J

How to Convert Kilojoule to Joule

1 kJ = 1000 J
1 J = 0.001 kJ

Example: convert 15 kJ to J:
15 kJ = 15 × 1000 J = 15000 J

Popular Energy Unit Conversions

Convert Kilojoule to Other Energy Units