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Kelvin

The kelvin (symbol: K) is a unit to measure temperature. It is one of the seven SI base units. It is defined by two factors: zero kelvin is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water (0.01 °C). The Celsius temperature scale is now defined in terms of the kelvin.

It is named after the physicist and engineer William Thomson, who became Lord Kelvin when he was made a peer.

The kelvin as an SI unit is correctly written with a lowercase k (unless at the beginning of a sentence), and is never preceded by the words degree or degrees, or the symbol °, unlike Fahrenheit, Celsius or centigrade. This is because the latter three are scales of measurement, whereas the kelvin is a unit of measurement.

 Conversion factors

kelvin to Celsius

$K - 273.15$

Celsius to kelvin

$C + 273.15$

kelvin to Fahrenheit

$(1.8 \times K) - 459.67$

Fahrenheit to kelvin

$\frac{(F + 459.67)}{1.8}$

electron volts to kelvin

$\frac{eV}{11,604}$

kelvin to electron volts

$K \times 11,604$