# Convert Fahrenheit to Kelvin

Please provide values below to convert Fahrenheit [°F] to kelvin [K], or *vice versa*.

### Fahrenheit

**Definition:** The Fahrenheit (symbol: °F) is a unit of temperature that was widely used prior to metrication. It is currently defined by two fixed points: the temperature at which water freezes, 32°F, and the boiling point of water, 212°F, both at sea level and standard atmospheric pressure. The interval between the freezing and boiling point is divided into 180 equal parts.

**History/Origin:** The Fahrenheit scale was developed based on a measurement proposed in 1724 by the German physicist Daniel Gabriel Fahrenheit. He initially based the scale on an equal ice-salt mixture, selecting the values of 30°F for the freezing point of water, and 90°F for normal body temperature. He later adjusted the scale such that the melting point of ice was 32°F and body temperature was 96°F. He chose these values to simplify the degree markings he could make on his instruments, since this difference between the temperatures allowed him to mark degree lines by bisecting the interval six times. Later, when using the freezing and boiling points of water as fixed reference points for thermometers became popular, the scale was slightly re-defined such that there would be 180 degrees separating freezing and boiling point, resulting in normal human body temperature being approximately 98°F, rather than Fahrenheit's 96°F.

**Current use:** Until the 1960's the Fahrenheit scale was the primary scale used in English-speaking countries. Today, most countries around the world use the Celsius temperature scale instead, many having made the change during their metrication processes (conversion to using the metric system of units). However, the Fahrenheit scale is still used as the official temperature scale in a number of countries, including the United States (as well as its unincorporated territories), the Bahamas, Belize, the Cayman Islands, and a few others.

### Kelvin

**Definition:** The kelvin (symbol: K) is the base unit of thermodynamic temperature in the International System of Units (SI). It is defined as the energy equivalent of the triple point of water as given by Boltzmann's equation. It is also the unit of the Kelvin scale in which the null point (0 K) is the temperature at which all thermal motion ceases, known as absolute zero, or -273.15°C. The definition of the kelvin was changed in 2019. This new definition results in a fundamental change in the kelvin, such that it is now dependent on the definitions of the second, the meter, and the kilogram.

**History/origin:** The kelvin is named after British physicist William Thomson, who was known as Lord Kelvin. Thomson wrote a paper outlining the need for an absolute temperature scale. He calculated the value of absolute zero to be -273°C in 1848 which is only a 0.15°C deviation from the current accepted value.

Until late 2018, the kelvin was defined as 1/273.16 of the thermodynamic temperature of the triple point of water (0.01°C or 32.018°F). This definition came about in 1954, when the General Conference on Weights and Measures designated the triple point of water as the second defining point of the Kelvin scale, defining the temperature as exactly 273.16 K.

Although the definition of the kelvin has changed fundamentally in 2019, it does not affect how the kelvin is used, or its relationship to other temperature scales and units.

**Current use:** The kelvin is used worldwide, particularly in science and engineering, together with the Celsius. This is partially due to the kelvin and the Celsius degree having exactly the same magnitude. Unlike the Celsius and Fahrenheit, the kelvin is not used in meteorological contexts.

### Fahrenheit to Kelvin Conversion Table

Fahrenheit [°F] | Kelvin [K] |
---|---|

0.01 °F | 255.3777777778 K |

0.1 °F | 255.4277777778 K |

1 °F | 255.9277777778 K |

2 °F | 256.4833333333 K |

3 °F | 257.0388888889 K |

5 °F | 258.15 K |

10 °F | 260.9277777778 K |

20 °F | 266.4833333333 K |

50 °F | 283.15 K |

100 °F | 310.9277777778 K |

1000 °F | 810.9277777778 K |

### How to Convert Fahrenheit to Kelvin

K = |
| (F + 459.67) |

F = |
| K - 459.67 |

**Example:** convert 50 °F to K:

50 °F = (50 + 459.67) × 5/9 = 283.15 K