Units & conversions


Temperature conversion formulas

Celsius to Kelvin

K = C + 273.15

Kelvin to Celsius

C = K - 273.15

Celsius to Fahrenheit

F = 9/5 (C) +32

Fahrenheit to Celsius

C = 5/9 (F - 32)

Fahrenheit to Kelvin

K = 9/5 (F + 459.67)

Fahrenheit to Kelvin

F = 5/9 K - 459.67

The kelvin (K) is the unit of thermodynamic temperature. It is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water (TPW).

The triple point of a substance is the temperature and pressure at which three phases (gas, liquid, and solid) of that substance may coexist in thermodynamic equilibrium. The triple point of water (TPW) occurs at a temperature of 273.16 K.

The degree Celsius (C) is the temperature unit of the International Temperature Scale of 1990 (ITS-90), adopted by the Comit international des poids et mesures (CIPM) in 1989. Historically, the scale was founded on the melting point of water, defined as 0 C, and on the boiling point of water, defined as 100 C, under normal atmospheric pressure (101325 Pa). Celsius remains a commonly adopted practical temperature scale. One kelvin is equal to one degree Celsius.

The degree Fahrenheit (F) is the temperature unit widely used in the United States. On this scale the melting point of ice water is 32 F and the boiling point is 212 F.