Temperature Converter | Fast & Accurate Conversions
Instantly convert temperatures between 8 different scales, including Celsius, Fahrenheit, Kelvin, and historical units like Réaumur and Rømer.
History of Temperature Scales
The way we measure temperature has evolved over centuries, with different scientists proposing scales based on various physical reference points.
Celsius (°C)
Proposed by Swedish astronomer Anders Celsius in 1742 (originally inverted). The modern form with 0 °C for freezing and 100 °C for boiling water was adopted shortly after and is now standard in science and most of the world.
Fahrenheit (°F)
Developed by Daniel Gabriel Fahrenheit in 1724. He based his scale on the temperature of a brine solution (0 °F), freezing water (32 °F), and human body temperature (conventionally ~98.6 °F). It is primarily used in the United States.
Kelvin (K)
Proposed by Lord Kelvin in 1848. The Kelvin scale is an absolute scale where 0 K is absolute zero—the point of minimum thermal energy (no classical thermal motion). It is the primary unit for temperature in the physical sciences.
Rankine (°R)
Developed by Scottish engineer William John Macquorn Rankine in 1859. It is an absolute scale based on the Fahrenheit degree, where 0°R is absolute zero (-459.67°F). It is used in some engineering fields in the U.S.
Delisle (°De)
Invented by French astronomer Joseph-Nicolas Delisle in 1732. This scale is inverted, with 0°De set at the boiling point of water and 150°De at its freezing point. It was popular in Russia for nearly a century.
Newton (°N)
Devised by Isaac Newton around 1700. He set 0°N as the freezing point of water and 33°N as its boiling point. It was a precursor to the Celsius scale and helped establish the use of two fixed points for calibration.
Réaumur (°Ré)
Created by René Antoine Ferchault de Réaumur in 1730. It sets the freezing point of water at 0°Ré and the boiling point at 80°Ré. It saw widespread use in Europe, particularly in France and Germany.
Rømer (°Rø)
Created by Danish astronomer Ole Rømer in 1701. This was one of the first calibrated scales, setting the freezing point of brine at 0°Rø, water’s freezing point at 7.5°Rø, and its boiling point at 60°Rø.
