According to the scale factor, the boiling point of water at 1 atmosphere is 100 degrees centigrade, 80 degrees Réaumur, 212 degrees Fahrenheit, 373.15 Kelvin and 617.67 degrees Rankine. The freezing point of water is zero degrees centigrade, zero degrees Réaumur, 32 degrees Fahrenheit, 273.15 Kelvin and 417.67 degrees Rankine. There are several ways of converting Kelvin into Fahrenheit, Celsius, Rankine or Réaumur

## Kelvin Scale

The Kelvin scale is commonly used in scientific calculation and is also referred to as the absolute temperature scale. On this scale the coldest temperature possible is minus 273 degrees centigrade and is considered as the zero Kelvin or the absolute zero. Thus, the Kelvin scale doesn’t have lower temperatures of less than zero degrees, so there are no negative values. Units on this scale are simply called Kelvin and are not denoted by degree values, and the size of the Kelvin is equal in size to that of the Celsius unit.

## Manual Conversion

Conversion to Kelvin is manually done by adding the value of 273.15 to the Celsius temperature. This is a straightforward calculation as long as the values given are in degrees centigrade. For example if the temperature given is at zero degrees centigrade the corresponding temperature is 273.15 Kelvin. The normal body temperature of 37 degrees centigrade is equivalent to 310.15 Kelvin. If the temperature is given in Fahrenheit, you first have to convert it into degrees centigrade using the formula F-32 then multiply by 5/9, where F is the temperature given in Fahrenheit, and then add 273.15 to change it into Kelvin.

## Online Calculators

There are several online calculators available that can assist in converting the temperature into Kelvin. The online calculators give a wide selection of choices such as converting Celsius to Kelvin, Fahrenheit to Kelvin and Rankine to Kelvin (see Resource 1). You need to select the appropriate choice depending on the variable the temperature is in; for example, if the temperature is given in Celsius, select the Celsius-to-Kelvin option and type the value in the box marked “Temperature in degree centigrade.” Press "Convert into Kelvin."

## Online Converters

There also numerous online metric converters that can be used in temperature conversion by typing the value to be changed from Kelvin into the box provided and pressing “Go.” These online programs provide options of conversion from Fahrenheit to Kelvin or degrees centigrade to Kelvin, Rankine to Kelvin, Reamur to Kelvin and vice versa (see Resources 2 and 3). They are easy to use and understand, making it possible to carry out multiple conversions within a short time.