Calorie to Megajoule Converter

A calorie (cal), also called a small calorie or gram calorie, is a unit of energy equal to approximately 4.184 joules. It represents the energy needed to raise the temperature of one gram of water by one degree Celsius at standard atmospheric pressure.

The calorie was defined by French chemist Nicolas Clément in 1824 as a unit for measuring heat. It was widely used in chemistry and physics for calorimetry and thermodynamics before being largely replaced by the joule in scientific applications, though it remains in use for food energy.

Calories are primarily used in chemistry for small-scale energy measurements, in some scientific literature, and occasionally in food and nutrition contexts. However, they've been largely replaced by joules in scientific applications and by kilocalories (food calories) in nutrition.

A megajoule (MJ) is a unit of energy equal to one million joules (10⁶ J). It represents moderate to large amounts of energy, commonly used for measuring food energy content, fuel values, and mechanical work in engineering applications.

The megajoule gained prominence with the development of energy-conscious engineering and nutrition science. It became particularly useful for expressing food energy content as an alternative to calories, and for measuring energy in automotive and mechanical engineering applications.

Megajoules are used in nutrition labeling (as an alternative to calories), automotive engineering, mechanical systems, and fuel energy content. They're found on food packaging in many countries, vehicle fuel efficiency ratings, and engineering calculations for mechanical work and heat transfer.