Calorie to Gigajoule 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 gigajoule (GJ) is a unit of energy equal to one billion joules (10⁹ J). It represents large amounts of energy, commonly used for measuring building energy consumption, industrial processes, and fuel energy content.

The gigajoule became important with the growth of energy-intensive industries and the need to measure energy consumption in large buildings and facilities. It provided a convenient scale for energy auditing, HVAC system sizing, and industrial energy management in the latter half of the 20th century.

Gigajoules are commonly used in building energy analysis, HVAC engineering, industrial energy management, and fuel energy content specifications. They're standard for measuring annual energy consumption of large buildings, industrial process energy requirements, and natural gas energy content.