Fahrenheit (temperature scale)

Scale and conversions

The size of one degree Fahrenheit is 5/9 of a degree Celsius. Standard conversion formulas are:

• Celsius to Fahrenheit: F = C × 9/5 + 32
• Fahrenheit to Celsius: C = (F − 32) × 5/9
• To Kelvin: K = (F − 32) × 5/9 + 273.15

History and development

The scale is named after Daniel Gabriel Fahrenheit, an 18th‑century instrument maker who developed reliable thermometers and proposed a practical temperature scale. He chose reference points based on mixtures of ice and salt and on the freezing point of water; the later convention of 32 °F for freezing and 212 °F for boiling became standard because of the convenient 180‑degree interval.

Uses, examples and context

Fahrenheit remains the primary public and meteorological scale in the United States. Typical reference values are: 32 °F (freezing of water), about 98.6 °F (normal human body temperature, approximate), 212 °F (boiling of water at sea level), and −459.67 °F for absolute zero. In many other countries Celsius is used for weather, science and industry.

Notable facts and distinctions

Fahrenheit degrees are smaller than Celsius degrees, which can make the scale feel more precise for describing everyday weather swings (for example, a 5‑degree Fahrenheit change is noticeable). Scientific work and most international applications use Celsius or Kelvin, while Fahrenheit persists in cultural and practical use in some regions.