Fahrenheit (°F) is a temperature scale where 32°F marks the freezing point of water and 212°F its boiling point, primarily used in the United States for weather, cooking, and everyday temperature references. It offers finer granularity than Celsius, with each degree representing a smaller temperature change. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9.

Kelvin (K) is the base unit of thermodynamic temperature in the International System of Units, where 0 K represents absolute zero, the theoretical point of zero thermal energy. Scientists use Kelvin in physics, chemistry, and astronomy because it starts at true zero with no negative values, making calculations straightforward. Zero degrees Celsius equals 273.15 Kelvin, and the two scales share the same size of degree increment.