Kelvin

SI Thermodynamics & ITS-90 Absolute Temperature Standards

The Kelvin (K) is defined by taking the fixed numerical value of the Boltzmann constant k = 1.380649 × 10^-23 J·K^-

• Absolute zero (0 K) is the lowest theoretical temperature where entropy and thermodynamic motion reach their minimum.

Primary Temperature Scale Reference Points

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

• Liquid Nitrogen Boiling Point: 77.36 K = -195.79^ = -320.42^

• Water Freezing Point: 273.15 K = 0.00^ = 32.00^ = 491.67^

• Standard Room Temperature: 293.15 K = 20.00^ = 68.00^

• Human Body Temperature: 310.15 K = 37.00^ = 98.60^

• Water Boiling Point: 373.15 K = 100.00^ = 212.00^ = 671.67^

• Solar Photosphere Surface: 5,778 K = 5,504.85^ = 9,940.73^

Equations

• T_^ = T_K - 273.15

• T_^ = (T_K - 273.15) × 1.8 + 32

• T_^ = T_K × 1.8

How to Use This Calculator

Enter your Absolute Temperature in Kelvin (K) (e.g. 293.15 in K). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Wien's Displacement Law: lambda_max = 2.897771955e6 nm-K / T

Worked Example

Standard room temperature of 293.15 K equals exactly 20.00°C (68.00°F), representing the baseline reference state for thermodynamic property tables.

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.