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Conversions

Celsius to Réaumur Converter.

Converts a temperature from degrees Celsius to degrees Réaumur, a historical temperature scale where water freezes at 0°Ré and boils at 80°Ré.

Results update live as you type.
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Your inputs

How it works

  1. 1

    Enter the temperature in degrees Celsius.

  2. 2

    Multiply the Celsius value by 0.8.

  3. 3

    The result is the temperature in degrees Réaumur.

celsius * 0.8

Frequently asked questions

What is the Réaumur scale?

The Réaumur scale sets the freezing point of water at 0°Ré and the boiling point at 80°Ré. It was widely used in Europe in the 18th and 19th centuries.

How do I convert Réaumur back to Celsius?

Multiply the Réaumur value by 1.25 (or divide by 0.8) to get degrees Celsius.

Is the Réaumur scale still used today?

It is mostly obsolete, but occasionally appears in historical documents and some old recipes or industrial processes.

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Results

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Temperature in Réaumur

20°Ré

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Estimate for general guidance only — verify important decisions with an appropriate professional.

How it works

Converts a temperature from degrees Celsius to degrees Réaumur, a historical temperature scale where water freezes at 0°Ré and boils at 80°Ré.

  1. Enter the temperature in degrees Celsius.
  2. Multiply the Celsius value by 0.8.
  3. The result is the temperature in degrees Réaumur.

Formulas

The math behind this calculator, written out so you can verify the result.

Celsius to Réaumur

°Ré = °C × 0.8

Since 100 Celsius degrees span 80 Réaumur degrees, each Celsius degree equals 0.8 Réaumur degrees.

Example:

Input: °C = 25

Calculation: 25 × 0.8

Result: 20°Ré

Real-world use cases

Where this calculation shows up in everyday life.

Historical research

Convert temperatures from old scientific papers or historical weather records that use Réaumur.

Example: Reading a 19th-century thermometer marked in °Ré.

Culinary heritage

Some traditional European recipes specify oven temperatures in Réaumur.

Example: A recipe calling for 30°Ré (about 37.5°C).

Educational purposes

Learn about temperature scales and their relationships.

Example: Comparing Celsius, Fahrenheit, and Réaumur.

Tips and common mistakes

Tips

  • Remember: 0°C = 0°Ré and 100°C = 80°Ré.
  • For quick mental conversion, multiply Celsius by 0.8.
  • Use the calculator for negative temperatures as well; the formula works for all values above absolute zero.

Common Mistakes to Avoid

  • Forgetting that the Réaumur scale has 80 degrees between freezing and boiling, not 100.
  • Using the Fahrenheit conversion factor (1.8) instead of 0.8.
  • Confusing Réaumur with Rankine or other temperature scales.

Assumptions and limitations

  • Use the stated inputs and units.
  • Results are estimates for planning and education.
  • Check measurements and source data before making an important decision.