# Temperature Conversion

## What is temperature conversion?

Temperature conversion is used for moving from one temperature scale to another at specific temperatures.

## Why are there different temperature scales?

There are different scales because there are different ways to measure and compare the level of thermal energy of an object or substance, which can be useful in various contexts. The reason why there are different temperature scales lies in the starting point and observation point of the phenomenon. The first attempts to measure temperature occurred at different places and times in history, and advances with these developed in separate ways. Therefore, it’s understandable that there was no unification among these until more global efforts in standardization were made.

## What temperature scales are there?

The three most common temperature scales today are Celsius (ºC), Fahrenheit (ºF), and Kelvin (K).

• The Celsius scale is based on water’s changes of state. The freezing point of water is 0ºC, and the boiling point is 100ºC. It’s the most widely used scale in the world in everyday environments. It is part of the International System of Units, so it is used in scientific contexts, though the use of Kelvin is required in most cases. “Degrees Celsius” is used interchangeably with “centigrade” in popular culture. This is because, since its origin, the scale was understood to be divided into one hundred parts between when water went from melting to when it would boil; however, the publication by the International Practical Temperature Scale suggests not using the term “centigrade.”
• The Fahrenheit scale was published before Celsius, and while it was very successful at first because of the mercury thermometers that its creator developed, it did not spread universally. Nowadays, it is only used in a few English-speaking countries, primarily the United States. Its decline in popularity was mainly due to the fact that the Fahrenheit scale was not based on fixed reference points of natural phenomena but on somewhat more arbitrary ones: the coldest point its inventor could reach with a solution of ice, water, and ammonium chloride, which he defined as zero on his scale; and his wife’s body temperature, which he interpreted as the body temperature of an average person. There are 180 degrees between the freezing point (32ºF) and boiling point of water (212ºF) on the scale.
• The Kelvin scale is the scale most commonly used in physics and chemistry. It is an absolute scale: its zero-point is absolute zero, or the coldest possible theoretical temperature in the universe, where all molecules of any substance would stop vibrating. Temperatures on the Kelvin scale are not expressed in degrees but in kelvins as a unit of measurement. This scale is also centigrade; that is, it is divided into intervals of 100 equal parts. The temperatures of the boiling and melting points of water are 373.16 K and 273.15 K, respectively.

There are many other scales, such as the Newton scale, where 0 degrees is the temperature at which snow melts and 33 degrees is the temperature at which water boils; the Rankine (R) scale; the Réaumur (°Ré) scale; the Rømer (°Rø) scale; and many others that are used for specific contexts or referred to for historical reasons.

How can you convert temperatures from one temperature scale to another?

This is a conversion table that explains the formulas used for the three most common temperature scales:

There are many integrated digital tools on mobile devices and web pages that perform temperature conversions automatically, calculating the different formulas to move from one scale to another.