Fahrenheit

Thermodynamic Temperature & ITS-90 Standards

Proposed by German-Dutch physicist Daniel Gabriel Fahrenheit in 1724, the scale set 0^ as the freezing point of an ammonium chloride brine and 96^ as body temperature (later calibrated to 32^ freezing and 212^ boiling).

Primary Temperature Scale Conversions

• Celsius: T_^ = T_^ - 321.8

• Kelvin: T_K = T_^ + 459.671.8

• Rankine: T_^ = T_^ + 459.67

• Réaumur: T_^é = (T_^ - 32) × (4) / (9)

Key Benchmarks

• Absolute Zero: -459.67^ = -273.15^ = 0 K

• Freezing Point of Water: 32^ = 0^ = 273.15 K

• Normal Human Body Temperature: 98.6^ = 37.0^ = 310.15 K

• Boiling Point of Water (Sea Level): 212^ = 100^ = 373.15 K

How to Use This Calculator

Enter your Temperature in Fahrenheit (°F) (e.g. 68.0 in °F). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Formula Reference: Fahrenheit

Input variables:

fahrenheitTemperature — Temperature in Fahrenheit (°F)

Computed outputs:

equivalentCelsius — Temperature in Celsius (°C)

equivalentKelvin — Temperature in Kelvin (K)

equivalentRankine — Temperature in Rankine (°R)

equivalentReaumur — Temperature in Réaumur (°Ré)

Mathematical relationships extracted from calculation logic:

tc = safeDiv(tf - 32.0, 1.8)

tk = safeDiv(tf + 459.67, 1.8)

tr = tf + 459.67

tre = (tf - 32.0) * (4.0 / 9.0)

Standard: NIST Handbook 44 and BIPM SI unit definitions

Worked Example

Setting a home thermostat to 68 °F corresponds to exactly 20.0 °C (293.15 K), meeting ASHRAE Standard 55 recommendations for optimal energy efficiency and indoor thermal comfort.

Understanding Your Result

Key temperature reference points: Absolute zero 0 K / −273.15°C / −459.67°F. Water freezes at 0°C / 32°F / 273.15 K. Water boils at 100°C / 212°F / 373.15 K at 1 atm (sea level). Human body temperature 37°C / 98.6°F. Oven baking range: 150–230°C / 300–450°F. Kelvin is always used in thermodynamic equations — never negative. Temperature differences in Celsius and Kelvin are equal: a 10°C rise = a 10 K rise.