Convert temperatures between Celsius, Fahrenheit, Kelvin, and Rankine scales instantly.
Celsius is a temperature scale where water freezes at 0° and boils at 100° at standard atmospheric pressure. It was formerly known as centigrade. The scale is named after Swedish astronomer Anders Celsius, who originally proposed it in 1742 with the opposite orientation (0° for boiling and 100° for freezing).
Fahrenheit is a temperature scale used primarily in the United States and its territories. Water freezes at 32°F and boils at 212°F at standard atmospheric pressure. The scale was proposed by German physicist Daniel Gabriel Fahrenheit in 1724. It was the first standardized temperature scale to be widely used.
Kelvin is the SI base unit of thermodynamic temperature. Absolute zero (0 K) is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. Water freezes at 273.15 K and boils at 373.15 K. The Kelvin scale uses the same degree increment as Celsius but starts at absolute zero.
Rankine is an absolute temperature scale used in engineering systems, particularly in the United States. It uses the same degree increment as Fahrenheit but starts at absolute zero (0°R = -459.67°F). The scale was proposed by Scottish engineer William John Macquorn Rankine in 1859. It is used in thermodynamics for calculating steam tables.