Converting units of temperature

Degrees Celsius and Kelvin

Kelvin is one of seven base SI units and is defined from 0K, which is absolute zero (absolute zero is the temperature at which all particle are motionless, however this is impossible to reach due to the third law of thermodynamics). Absolute zero is equivalent to -273.15°C.

The other temperature scale is Celsius which is defined by two fixed points, the temperature at which ice melts (0°C = 273.15K) and the melting point (100°C = 373.15K). 

One degree difference is the same for both Celsius and Kelvin. 

Degrees Celsius a Fahrenheit

Fahrenheit is another type of temperature scale, now primarily used in the USA and its territories. Unlike Celsius and Kelvin temperature scale, the temperature difference between the melting and boiling point is 180 degrees.

The melting point is 32°F a boiling point is 212 °F.

The conversion from Celsius to Fahrenheit is more complicated (beside -40°F which is equal to -40°C). We first need to adjust the size of one degree. The difference between the melting and boiling point is 180°F but 100°C so the ratio is 9:5. The melting point is 0°C and 32°F so that must also be adjusted. These two adjustments combined are how degrees Celsius are converted to Fahrenheit and vise versa. 

Degrees Fahrenheit and Kelvin

Absolute Zero is -459.67 °F.

Conversions between °C a °F

Converting units of temperature questions and answers

• What is the Fahrenheit temperature scale based on?

  Fahrenheit is based on three point - that of freezing water, human body temperature and the coldest point to which Fahrenheit (the scientist behind this scale) could cool a body of water.

• What is the Celsius temperature scale based on?

  The Celsius scale is based on freezing point of water (0°C) and boiling point of water (100°C). Every other point on the scale is relative to that.