Fahrenheit (°F)
Definition
The Fahrenheit scale (symbol °F) is a temperature scale on which water freezes at 32 °F and boils at 212 °F at standard atmospheric pressure, giving a 180-degree interval between the two reference points. It remains the standard scale for weather and everyday temperatures in the United States.
History
The German physicist Daniel Gabriel Fahrenheit introduced his scale in 1724, using a brine freezing point as 0, the freezing point of pure water as 32, and roughly human body temperature as 96. He chose values that let him use the longer mercury thermometers he produced.
Britain and her colonies adopted Fahrenheit through the eighteenth and nineteenth centuries. Most of the Commonwealth switched to Celsius from the 1960s onward, leaving the United States and a handful of small territories as the primary users today. The scale is defined relative to Celsius and ultimately the kelvin.
Standard reference
Defined relative to Celsius: T(°F) = T(°C) × 9/5 + 32. NIST Special Publication 811 lists this as the official conversion relationship.
Common conversions
| 32 °F | = 0 °C |
|---|---|
| = 273.15 K | |
| = 491.67 °R |