Celsius

Thermodynamic Temperature & ITS-90 Standards

The International Temperature Scale of 1990 (ITS-90) defines temperature relative to the triple point of water and absolute zero.

Primary Temperature Conversion Equations

• Celsius to Fahrenheit: T_^ = (T_^ × 1.8) + 32 = ( T_^ × (9) / (5) ) + 32

• Celsius to Kelvin: T_K = T_^ + 273.15

• Celsius to Rankine: T_^ = 1.8

• Celsius to Réaumur: T_^é = T_^ × 0.8

Notable Benchmarks

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

• Water Freezing Point: 0.0^ = 32.0^ = 273.15 K

• Human Body Temp: 37.0^ = 98.6^ = 310.15 K

• Water Boiling Point: 100.0^ = 212.0^ = 373.15 K

How to Use This Calculator

Enter your Temperature in Celsius (°C) (e.g. 25.0 in °C). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Formula Reference: Celsius

Input variables:

celsiusTemperature — Temperature in Celsius (°C)

Computed outputs:

equivalentFahrenheit — Fahrenheit (°F)

equivalentKelvin — Kelvin (K)

equivalentRankine — Rankine (°R)

equivalentReaumur — Réaumur (°Ré)

Mathematical relationships extracted from calculation logic:

f = (c * 1.8) + 32.0

k = c + 273.15

r = (c + 273.15) * 1.8

re = c * 0.8

Standard: NIST Handbook 44 and BIPM SI unit definitions

Worked Example

A comfortable room temperature of 25 °C translates to 77 °F in the United States and 298.15 K in thermodynamic physics calculations.

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.