Réaumur to Kelvin (°Ré to K)
1 degree Réaumur equals 274.4 kelvins.
How to convert degrees Réaumur to kelvins
Converting degrees Réaumur to kelvins is not a simple multiplication, so use the formula below.
K = °Ré × 1.25 + 273.15
Example: 10 degrees Réaumur = 285.65 kelvins.
Temperature scales have different zero points, so converting is not just multiplication. Differences in degrees convert differently from absolute readings.
About these units
Degree Réaumur (°Ré)
A scale proposed in 1730 by René Réaumur in which water freezes at 0° and boils at 80°. Used across Europe until the 19th century and in Russia until the early 20th.
René Antoine Ferchault de Réaumur proposed a thermometer scale in 1730, and it still carries his name. He placed zero at the melting point of water and divided the tube so that each degree was one thousandth of the volume of the bulb and stem below the zero mark. His liquid was diluted alcohol, mixed so that it began to boil after expanding by 8 percent, which gave the familiar 80 degrees for boiling water. The method is also called the octogesimal division.
Instrument makers often filled their tubes with other liquids while still marking 80 for boiling water, which caused real confusion until mercury became nearly universal from the late 18th century, following Jean-André Deluc's tests in 1772. The scale was common in France, Germany and Russia, and appears in the writing of Jefferson, Dostoevsky and Tolstoy. France moved to the centigrade scale in the 1790s, but Réaumur readings lingered in parts of Europe until at least the mid-19th century and in parts of Russia into the early 20th.
Because the interval from freezing to boiling is 80 degrees instead of 100, one degree Réaumur equals 1.25 degrees Celsius, so Celsius is the Réaumur reading times 5/4. Kelvin is that figure plus 273.15. Today the scale survives mainly among some Italian and Swiss cheesemakers, who use it for milk temperatures.
0 degrees Réaumur = 273.15 kelvins (exactly).
Sources: Wikipedia: Réaumur scale
Kelvin (K)
The SI base unit of temperature. Zero kelvin is absolute zero, where particles have minimal thermal motion. A kelvin step is the same size as a Celsius degree.
Lord Kelvin, born William Thomson, published an absolute temperature scale in 1848 and refined it with James Joule in 1854. Its zero sits at absolute zero, and its degree is the same size as a Celsius degree. The kelvin entered the SI in 1954, defined as 1/273.16 of the thermodynamic temperature of the triple point of water, where ice, liquid and vapor coexist. In 1967 the 13th CGPM renamed the unit from the degree Kelvin to simply the kelvin, with symbol K, and no word degree.
Since 20 May 2019 the kelvin has been defined by fixing the Boltzmann constant at exactly 1.380649 times 10 to the minus 23 joule per kelvin, which frees it from the properties of any one substance. Scientists use it for stars and cryogenics, and lighting designers use it for color temperature. NIST notes that incandescent bulbs run near 3,000 K, daylight lamps at 5,000 to 5,600 K, and the Sun's surface at about 5,800 K. Room temperature, about 21 degrees Celsius, is roughly 294 K.
The kelvin is the reference unit for temperature on this site.
Sources: NIST: the kelvin and the SI redefinition; BIPM: 13th CGPM (1967), Resolution 3; Wikipedia: Kelvin
Related conversions
- Kelvin to Réaumur (reverse)
- Réaumur to Celsius
- Réaumur to Fahrenheit
- Celsius to kelvin
- Fahrenheit to kelvin
- Rankine to kelvin
- Delisle to kelvin
- Newton to kelvin
- Rømer to kelvin
See all temperature units.