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Metric (S.I.)
21 °C = 294.15 KKelvin
21 °C = 18.53 °RøRømer
21 °C = 118.50 °DeDelisle
21 °C = 21.00 °CCelsius
21 °C = 6.93 °NNewton
21 °C = 16.80 °RéRéaumur
21 °C = 529.47 °RRankine
US, Anglo-saxon
21 °C = 69.80 °FFahrenheit




Celsius, Fahrenheit, Kelvin ....

The degree Celsius (symbol C or 1 ℃) is the unit of the Celsius temperature scale, which is a derived unit of the international system of units, introduced in 1948. His name is a reference to the Swedish astronomer and physicist Anders Celsius, inventor in 1742 of one of the first centigrade temperature scale.

Degree Fahrenheit (℉) is a unit of temperature measurement, which is named after the German physicist Daniel Gabriel Fahrenheit, who proposed in 1724.

Scale Newton is a scale for measuring temperature, developed around 1700 by English physicist Isaac Newton.

kelvin (symbol K, named after Lord Kelvin) is the SI unit of thermodynamic temperature. The Celsius temperature scale is, by definition, the absolute temperature shifted origin of 273.15 K:

  • T = 273.15 + t, with t, the temperature in ° C and T, the temperature in K.

  • Absolute zero is located at -273.15 ° C.

  • intervals of the scale of the degree Celsius are the same as the kelvin.

Scale Rankine is a temperature scale named after the Scottish engineer and physicist William John Macquorn Rankine, who proposed in 1859. As Kelvin, Rankine zero is absolute zero, but Fahrenheit is used.

Scale Delisle is a temperature scale designed in 1732 by the French astronomer Joseph-Nicolas Delisle (1688-1768)

Scale Reaumur is a temperature scale designed in 1731 by French physicist and inventor (Vendée) René-Antoine de Reaumur Ferchault (1683-1757), who defined his thermometer from the apparent expansion of alcohol and calibrating a reference range between the freezing point of water (value zero) and the boiling point of water (value 80).

Scale Rømer (also spelled Roemer) is a temperature scale developed by the astronomer, physicist and maker of measuring instruments Ole Christensen Rømer of Denmark in 1701.

Use in the world

Fahrenheit scale was widely used in Europe until it is replaced by the scale of Celsius. It is still used today in the United States and in some English-speaking countries.