Convert Celsius to Fahrenheit

Celsius

Definition: The Celsius (symbol: °C) is an SI (International System of Units) derived unit of temperature. It is defined based on the SI unit of temperature, the kelvin. The Celsius and Kelvin scales are precisely related, with a one-degree change in Celsius being equal to a one degree-change in kelvin. The kelvin (and thus Celsius) is defined based on the Boltzmann constant, k, which equals 1.380649 × 10-23 when expressed in the unit J·K-1, a unit equivalent to kg·m2·s-2·K-1. The kilogram, meter, and second, are defined based on Planck's constant, h, the speed of light, c, and cesium frequency, ΔνCs.

History/origin: From 1743 until 1954, the Celsius scale was based on 0°C for the freezing point of water and 100 °C for the boiling point of water, both at a pressure of one standard atmosphere, using mercury as the working material. This was not always the case, and originally 0°C was defined as the boiling point of water and 100°C was defined as the melting point of snow. Celsius as a unit and a scale was not widely used until this original definition was inverted. In 1954, the unit, "degree Celsius," as well as the Celsius scale were again re-defined to instead be based on absolute zero (-273.15 °C) and the triple point of VSMOW (specially purified water). This is the definition that was used up until 2019, when the kelvin was redefined based on the definitions of the second, meter, and kilogram.

Current use: The Celsius scale replaced the Fahrenheit scale in most countries in the mid to late 20th century. Almost all countries around the world use this scale, except for those in which the metric system has not been adopted, such as the United States. Even in countries like the United States however, Celsius is widely used within the scientific community—it just is not widely used in everyday temperature references.

Fahrenheit

Definition: The Fahrenheit (symbol: °F) is a unit of temperature that was widely used prior to metrication. It is currently defined by two fixed points: the temperature at which water freezes, 32°F, and the boiling point of water, 212°F, both at sea level and standard atmospheric pressure. The interval between the freezing and boiling point is divided into 180 equal parts.

Current use: Until the 1960's the Fahrenheit scale was the primary scale used in English-speaking countries. Today, most countries around the world use the Celsius temperature scale instead, many having made the change during their metrication processes (conversion to using the metric system of units). However, the Fahrenheit scale is still used as the official temperature scale in a number of countries, including the United States (as well as its unincorporated territories), the Bahamas, Belize, the Cayman Islands, and a few others.