Calories (cal) to Joules (J) Conversion

Calories

The calorie (cal) is a unit of energy equal to exactly 4.184 joules, defined as the energy required to raise the temperature of one gram of water by one degree Celsius at 15 °C. This is the thermochemical calorie — distinct from the food calorie (written as Cal or kcal), which is 1,000 times larger. The calorie originated in 19th-century thermodynamics before the joule was established as the SI standard, and persists in chemistry, biology, and food science.

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.

Convert Calories (cal) to other units of Energy