Convert celsius to réaumur in 2 seconds flat

Picture this: you're reading a 19th century French cookbook, and the recipe calls for baking at 80 degrees réaumur. Your oven only shows celsius. That's exactly why we built this tool. While réaumur isn't exactly everyday knowledge now, it hides in cheese caves, antique science journals, and European family recipes. Let's break down this temperature tango.

Unit definitions

What is a celsius (°C)?

• Description: The modern metric temperature scale
• Symbol: °C
• Common uses: Weather reports, cooking, scientific research
• Definition: 0°C = water freezing point, 100°C = boiling point (at sea level)

What is a réaumur (°Re)?

• Description: Historical scale from the Age of Enlightenment
• Symbol: °Ré, °Re, or °R
• Common uses: Traditional cheese production, historical documents
• Definition: 0°Re = water freezing point, 80°Re = boiling point

Conversion formula

Multiply celsius by 0.8 to get réaumur:
°Re = °C × 0.8

To go the other way:
°C = °Re ÷ 0.8

Example calculations

1. Room temperature (20°C to réaumur):
   20 × 0.8 = 16°Re
   That's why 20°C feels like 16°Re in your grandma's wine cellar.
2. Winter day (-5°C to réaumur):
   -5 × 0.8 = -4°Re
   Negative values stay negative - no tricky math here.

Conversion tables

Celsius to réaumur

Réaumur to celsius

Historical background

René Antoine Ferchault de Réaumur proposed his scale in 1730, using alcohol thermometers. Anders Celsius introduced his inverted version (originally 0°=boiling, 100°=freezing) in 1742. The two scales coexisted for centuries, with réaumur dominating Europe until metrication efforts phased it out. Fun fact, the original celsius scale was flipped! We use Jean-Pierre Christin's 1743 modification where 0°C means freezing.

You might spot réaumur in Dostoevsky novels or Swiss Gruyère production logs. Some Alpine cheesemakers still prefer it because "80°Re" sounds more precise than "100°C" for milk pasteurization, though technically they're equivalent when you do the math.

Interesting facts

1. Napoleon's army used réaumur thermometers during the Russian campaign
2. 1°Re equals 1.25°C - making mental math possible
3. Russia used réaumur until the 1920s revolution
4. The scale survives in some Italian grappa distilleries
5. Réaumur's 80-degree boiling point was chosen for easy quadrant division

FAQ