Celsius to Reaumur Converter
Enter the value that you want to convert Celsius (°C) to Reaumur (°r) or Reaumur to Celsius.Also written as °C to °R conversion.
1 Celsius = 0.8000000 Reaumur
Formula: °Ré = °C × 4/5
°C to °R — Celsius to Reaumur
10 Celsius = 8.00000 Reaumur
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Converting Celsius to Reaumur
Understanding the Celsius
The Celsius scale was proposed by Swedish astronomer Anders Celsius in 1742, originally with 0° as the boiling point and 100° as freezing — later inverted.
Celsius (°C) is the most widely used temperature scale globally, adopted by every country except the United States for everyday use. It sets water's freezing point at 0°C and boiling point at 100°C at standard atmospheric pressure. The scale is used in weather forecasts, cooking, medicine (normal body temperature ≈ 37°C), scientific research, and industrial processes worldwide. Since 1954, it has been defined relative to the Kelvin scale: °C = K − 273.15.
Understanding the Reaumur
The Réaumur scale sets water's freezing point at 0° and boiling point at 80°, created by French scientist René Antoine Ferchault de Réaumur in 1730.
Once widely used in Europe (particularly France, Germany, and Russia), the Réaumur scale (°Ré) has been almost entirely replaced by Celsius. However, it persists in some traditional industries: Italian and Swiss cheese-making (specifying milk temperatures during production), some French cooking traditions, and historical weather records. The scale is notable for having only 80 divisions between freezing and boiling, making each Réaumur degree 1.25 Celsius degrees.
Temperature Scales in Context
Temperature conversion is one of the few non-linear unit conversions people encounter daily. Celsius dominates scientific work and most countries, Fahrenheit remains standard in the US for weather and cooking, Kelvin is required in thermodynamics and gas law calculations, and Rankine appears in some US engineering applications. Converting between these scales requires formulas rather than simple multiplication.
Celsius to Reaumur metric conversion table
| 0.01 °C | = | 0.00800 °r |
| 0.1 °C | = | 0.08000 °r |
| 1 °C | = | 0.80000 °r |
| 2 °C | = | 1.60000 °r |
| 3 °C | = | 2.40000 °r |
| 4 °C | = | 3.20000 °r |
| 5 °C | = | 4.00000 °r |
| 6 °C | = | 4.80000 °r |
| 7 °C | = | 5.60000 °r |
| 8 °C | = | 6.40000 °r |
| 9 °C | = | 7.20000 °r |
| 10 °C | = | 8.00000 °r |
| 11 °C | = | 8.80000 °r |
| 12 °C | = | 9.60000 °r |
| 13 °C | = | 10.40000 °r |
| 14 °C | = | 11.20000 °r |
| 15 °C | = | 12.00000 °r |
| 16 °C | = | 12.80000 °r |
| 17 °C | = | 13.60000 °r |
| 18 °C | = | 14.40000 °r |
| 19 °C | = | 15.20000 °r |
| 20 °C | = | 16.00000 °r |
| 30 °C | = | 24.00000 °r |
| 40 °C | = | 32.00000 °r |
| 50 °C | = | 40.00000 °r |
| 60 °C | = | 48.00000 °r |
| 70 °C | = | 56.00000 °r |
| 80 °C | = | 64.00000 °r |
| 90 °C | = | 72.00000 °r |
| 100 °C | = | 80.00000 °r |
| 200 °C | = | 160.00000 °r |
| 300 °C | = | 240.00000 °r |
| 400 °C | = | 320.00000 °r |
| 500 °C | = | 400.00000 °r |
| 600 °C | = | 480.00000 °r |
| 700 °C | = | 560.00000 °r |
| 800 °C | = | 640.00000 °r |
| 900 °C | = | 720.00000 °r |
| 1000 °C | = | 800.00000 °r |
How to Convert °C to °R (Celsius to Reaumur)?
We can convert Celsius to Reaumur by using an example.
Example:
Convert 20 Celsius to Reaumur?
We know 1 Celsius = 0.8000000 Reaumur; 1 Reaumur = 1.2500000 Celsius.
20 Celsius = ___°r
20 × 0.8000000 = 16.00000 °r (we know 1 Celsius = 0.8000000 Reaumur)
Answer:
20 Celsius = 16.00000 Reaumur
How to Convert Celsius to Réaumur
The Réaumur scale has 80 divisions between freezing and boiling (vs 100 for Celsius). Formula: °Ré = °C × 4/5:
- Write down the Celsius temperature.
- Multiply by 4/5 (or 0.8).
- The result is Réaumur.
Solved Examples
Question 1: Convert 100°C to Réaumur.
Solution:
°Ré = 100 × 4/5
= 80
Answer: 100°C = 80°Ré (boiling point on both scales)
Question 2: Convert 37°C (body temperature) to Réaumur.
Solution:
°Ré = 37 × 0.8
= 29.6
Answer: 37°C = 29.6°Ré
Question 3: Milk for cheese-making is heated to 32°C. Réaumur?
Solution:
°Ré = 32 × 0.8
= 25.6
Answer: 32°C = 25.6°Ré
Practice Questions
Try solving these on your own to test your understanding:
- Convert 50°C to Réaumur. (Answer: 40°Ré)
- What is -20°C in Réaumur? (Answer: -16°Ré)
- Convert 75°C to Réaumur. (Answer: 60°Ré)
Réaumur in Traditional Cheese-Making
Italian Parmigiano-Reggiano and Swiss Gruyère production manuals historically specify milk temperatures in Réaumur. "Heat to 25-26 degrees" in a traditional recipe means 25-26°Ré = 31.25-32.5°C. Some artisanal cheese makers in France and Italy still use antique Réaumur thermometers. Understanding this scale helps interpret centuries-old food production records.
Key Takeaways
- °Ré = °C × 4/5 (multiply by 0.8).
- 0°C = 0°Ré, 100°C = 80°Ré.
- Each Réaumur degree is 1.25 Celsius degrees.
- Still used in some European food traditions.
Celsius to Reaumur Conversion Formula
°Ré = °C × 4/5
1 Celsius = 0.8000000 Reaumur
1 Reaumur = 1.2500000 Celsius
Frequently Asked Questions
How many Reaumur are in 1 Celsius?
1 Celsius equals 0.80000 Reaumur. Note: Temperature conversion uses a formula, not simple multiplication.
How do I convert Celsius to Reaumur?
Use the conversion formula shown above. For example, 4.00 Reaumur equals 5 Celsius. Temperature scales have different zero points, so a formula (not simple multiplication) is required.
How do I convert Reaumur to Celsius?
Use the reverse formula. 1 Reaumur equals 1.25000 Celsius. See the formula section above for the exact equation.
What is 10 Celsius in Reaumur?
10 Celsius is equal to 8.00000 Reaumur.
What is 100 Celsius in Reaumur?
100 Celsius is equal to 80.00000 Reaumur.