Kilojoules (kJ) to Joules (J) Conversion
Kilojoules
The kilojoule (kJ) is a unit of energy equal to exactly 1,000 joules. It is the standard unit for expressing food energy in most countries outside the United States, where food labels display energy in both kilojoules and kilocalories (kcal). One kilocalorie equals exactly 4.184 kilojoules. In thermodynamics and chemistry, reaction enthalpies and bond energies are commonly tabulated in kilojoules per mole (kJ/mol).
Joules
The joule (J) is the SI derived unit of energy, work, and heat, defined as the work done when a force of one newton displaces an object by one metre (J = N·m = kg·m²·s⁻²). Named after James Prescott Joule, who established the mechanical equivalent of heat in the 1840s, the joule unifies all forms of energy — mechanical, thermal, electrical, chemical, and nuclear — under one framework. One joule is small: lifting an apple (≈100 g) one metre requires about 1 joule, while a human at rest metabolises approximately 80 joules per second.
| Kilojoules (kJ) | Joules (J) |
|---|---|
| 0.1 kJ | 100 J |
| 1 kJ | 1000 J |
| 2 kJ | 2000 J |
| 3 kJ | 3000 J |
| 5 kJ | 5000 J |
| 10 kJ | 10000 J |
| 20 kJ | 20000 J |
| 30 kJ | 30000 J |
| 50 kJ | 50000 J |
| 100 kJ | 100000 J |
| 1000 kJ | 1000000 J |