Celsius to Delisle (°C to °De)
1 degree Celsius equals 148.5 degrees Delisle.
How to convert degrees Celsius to degrees Delisle
Converting degrees Celsius to degrees Delisle is not a simple multiplication, so use the formula below.
°De = °C × -1.5 + 150
Example: 10 degrees Celsius = 135 degrees Delisle.
Temperature scales have different zero points, so converting is not just multiplication. Differences in degrees convert differently from absolute readings.
About these units
Degree Celsius (°C)
The metric temperature scale used worldwide for weather and daily life: water freezes at 0 °C and boils at 100 °C at standard pressure. Named after Anders Celsius.
Anders Celsius, a Swedish astronomer, proposed a scale in 1742 that ran the opposite way from the one we use: 0 for the boiling point of water and 100 for its freezing point. Credit for flipping it is shared and partly disputed. French physicist Jean-Pierre Christin published a reversed mercury thermometer in 1743, Carl Linnaeus is usually credited with reversing it in 1744, the year Celsius died, and others in Sweden, including Pehr Elvius, Daniel Ekström and Mårten Strömer, are also named as independent developers.
For much of the nineteenth century the scale was called centigrade, until the CGPM and CIPM adopted the name degree Celsius in 1948, partly to honor Celsius and to avoid confusion with a French term for a subdivision of the gradian. From 1954 to 2019 it was defined through absolute zero and the triple point of water; since 2019 it is tied to the Boltzmann constant. Strictly, water boils at about 99.974 degrees on the modern international temperature scale, not exactly 100. Australian weather reports switched exclusively to Celsius in 1972.
0 degrees Celsius = 273.15 kelvins (exactly).
Sources: Wikipedia: Celsius; BIPM: 9th CGPM (1948), Resolution 7; NIST: the kelvin and the SI redefinition
Degree Delisle (°De)
An inverted scale devised by Joseph-Nicolas Delisle in 1732 and later fixed with water boiling at 0° and freezing at 150°, so temperatures rise as it gets colder. Used in Russia for roughly a century.
Temperatures on the Delisle scale rise as things get colder, a reversal found in very few thermometer systems. Joseph-Nicolas Delisle, a French astronomer, built a mercury thermometer in 1732 with zero at the boiling point of water and measured the contraction of the mercury in hundred-thousandths. Peter the Great had invited him to Russia in 1725 to found an observatory in St. Petersburg, and his instruments were usually graduated to 2,400 or 2,700 divisions, a range suited to the severe local winters.
In 1738 Josias Weitbrecht, a colleague in St. Petersburg, recalibrated the instrument between two fixed points, 0 for boiling water and 150 for freezing. He sent such thermometers to scholars, among them Anders Celsius, whose own first scale was also inverted, running from 0 at boiling to 100 at freezing, before it was flipped after his death. Wikipedia says the Delisle thermometer stayed in use in Russia for almost a century, though that claim lacks a citation.
One degree Delisle is two thirds of a kelvin or Celsius degree. To convert, subtract two thirds of the Delisle reading from 100 to get Celsius, or from 373.15 to get kelvin. Boiling water is therefore 0 and freezing water is 150, so an ordinary winter day reads well above 100.
0 degrees Delisle = 373.15 kelvins (exactly).
Sources: Wikipedia: Delisle scale
Related conversions
- Delisle to Celsius (reverse)
- Celsius to kelvin
- Celsius to Fahrenheit
- Celsius to Rankine
- Celsius to Réaumur
- Celsius to Newton
- Celsius to Rømer
- Kelvin to Delisle
- Fahrenheit to Delisle
See all temperature units.