# Celsius

The Celsius (°C) temperature scale is used for measuring temperature in the metric system. It is the most widely used temperature scale globally, with the exception of the United States and its territories, which use the Fahrenheit scale for everyday purposes.

Two reference points for this temperature scale are:

0° - the freezing point of water

100° - the boiling point of water

The freezing and boiling points of water were part of the definition of the Celsius scale for a long period of time (1743-1954). It was redefined in 1954 to be based on absolute zero and the triple point of water, which related the Celsius scale precisely to the Kelvin scale. Today, the definition of the Celsius is still linked directly to the Kelvin scale, except that the kelvin is now defined based on the Boltzmann constant, and the triple point of water is no longer used as part of the definition of the Kelvin or Celsius scales.

## Converting Celsius to Fahrenheit

Although most countries use Celsius, it can be useful to know how to convert a temperature in Celsius to one in Fahrenheit, or the other way round. Below are the formulas for doing so, where we will use f to refer to a temperature in Fahrenheit, and c to refer to a temperature in Celsius.

• Celsius to Fahrenheit: (c × ) + 32 = f
• Fahrenheit to Celsius: (f - 32) × = c

The following converter can be used to convert from Celsius to Fahrenheit or Fahrenheit to Celsius. Just enter a value in either Celsius or Fahrenheit to convert between the two.

 Celsius Fahrenheit

Examples

1. Convert 100 °C to Fahrenheit:

(100 °C × ) + 32 = 212 °F

2. Convert 87 °F to Celsius:

(87 - 32) × = 30.56 °C