Calorie to Therm 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 therm (thm) is a unit of energy equal to 100,000 BTUs or approximately 105.5 megajoules. It's commonly used for measuring natural gas consumption and energy content in the United States gas industry.

The therm was introduced in the early 20th century by the gas industry in the United States as a convenient unit for measuring and billing natural gas consumption. It provided a practical scale for residential and commercial gas usage where BTUs would result in large numbers.

Therms are primarily used in the United States for natural gas billing, gas appliance ratings, and energy content specifications for natural gas. They're found on residential and commercial gas bills, used in gas utility planning, and for measuring heating energy consumption.