scale based on 32° for the freezing point of water and 212° for the boiling point of water, the interval between the two being divided into 180 equal parts. The 18th-century German physicist Daniel Gabriel Fahrenheit (Fahrenheit, Daniel Gabriel) originally took as the zero of his scale the temperature of an equal ice-salt mixture and selected the values of 30° and 90° for the freezing point of water and normal body temperature, respectively; these later were revised to 32° and 96°, but the final scale required an adjustment to 98.6° for the latter value.

The Fahrenheit temperature scale is used in the United States; the Celsius (Celsius temperature scale), or centigrade, scale is employed in most other countries and for scientific purposes worldwide. The conversion formula for a temperature that is expressed on the Celsius (°C) scale to its Fahrenheit (°F) representation is: