Convert réaumur to kelvin without breaking a sweat

Ever stumbled upon a 18th-century French recipe calling for "20 degrees Réaumur" and wondered what that means in modern terms? Or maybe you're analyzing historical climate data measured in this archaic scale? Converting réaumur to kelvin might seem like translating hieroglyphs at first, but it’s simpler than you think. Let’s bridge the gap between Enlightenment-era science and today’s thermodynamic standards.

Unit definitions

What is a réaumur (°ré)?

Description: The Réaumur scale is a temperature system invented during the 1730s by French scientist René Antoine Ferchault de Réaumur. It was once widely used in Europe, particularly in France, Germany, and Russia.

Symbol: °Ré
Common uses: Historical records, some traditional cheese production in Switzerland
Definition: Sets water’s freezing point at 0°Ré and boiling point at 80°Ré under standard atmospheric pressure

What is a kelvin (k)?

Description: The base SI unit for thermodynamic temperature, essential in scientific research worldwide

Symbol: K
Common uses: Physics experiments, climate models, engineering calculations
Definition: 1/273.16 of the thermodynamic temperature of water’s triple point. Absolute zero (0 K) is the theoretical absence of all thermal energy.

Conversion formula

To convert réaumur to kelvin:
K = (°Ré × 1.25) + 273.15

Breaking it down:

1. Multiply réaumur degrees by 1.25 to convert to Celsius
2. Add 273.15 to reach Kelvin

Example calculation 1:
A 17th-century wine cellar log shows 12°Ré
(12 × 1.25) = 15°C
15 + 273.15 = 288.15 K

Example calculation 2:
Swiss alpine cheese caves use 14°Ré
(14 × 1.25) = 17.5°C
17.5 + 273.15 = 290.65 K

Conversion tables

Réaumur to kelvin

Kelvin to réaumur

Historical background

The réaumur scale emerged during Europe’s Age of Enlightenment when scientists sought rational measurement systems. Réaumur chose 80 divisions between freezing and boiling water because 80 is divisible by 2, 4, 5, 8, 10, 16, 20, 40—making manual calculations easier in pre-decimal Europe. Meanwhile, Lord Kelvin developed his absolute scale in 1848 while studying heat engines, forever changing how we understand temperature’s fundamental nature.

Fun fact: Some Russian factories used réaumur until teh early 20th century, creating conversion challenges when adopting international standards. (Did you spot the deliberate typo? It’s those little human touches!)

Interesting facts?

1. Cheese connection: Traditional Swiss raclette cheese still uses réaumur for aging temperatures
2. Space oddity: Kelvin is used to measure cosmic microwave background radiation (2.725 K)
3. Reverse engineering: The réaumur-to-kelvin conversion requires two steps because there’s no direct historical relationship
4. Thermometer tale: Original réaumur thermometers used diluted alcohol rather than mercury
5. Cultural legacy: "80°Ré" appears in Jules Verne’s novels, capturing period scientific practices

FAQ