Conversions

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Conversions

Réaumur to Celsius Converter.

Converts a temperature from the Réaumur scale to Celsius. The Réaumur scale sets the freezing point of water at 0°Ré and boiling point at 80°Ré.

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Your inputs

How it works

  1. 1

    Enter the temperature in degrees Réaumur.

  2. 2

    Multiply the Réaumur value by 1.25.

  3. 3

    The result is the temperature in degrees Celsius.

reaumur * 1.25

Frequently asked questions

What is the Réaumur scale?

The Réaumur scale is a temperature scale where water freezes at 0°Ré and boils at 80°Ré. It was widely used in Europe in the 18th and 19th centuries.

How do I convert Celsius to Réaumur?

To convert Celsius to Réaumur, divide the Celsius temperature by 1.25. For example, 25°C ÷ 1.25 = 20°Ré.

Is the Réaumur scale still used today?

It is rarely used today, but it appears in historical documents and some old recipes, especially in France and Germany.

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Temperature in Celsius

0°C

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

How it works

Converts a temperature from the Réaumur scale to Celsius. The Réaumur scale sets the freezing point of water at 0°Ré and boiling point at 80°Ré.

  1. Enter the temperature in degrees Réaumur.
  2. Multiply the Réaumur value by 1.25.
  3. The result is the temperature in degrees Celsius.

Formulas

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

Réaumur to Celsius

°C = °Ré × 1.25

Since 80°Ré equals 100°C, each degree Réaumur is 100/80 = 1.25 degrees Celsius.

Example:

Input: °Ré = 40

Calculation: 40 × 1.25

Result: 50°C

Real-world use cases

Where this calculation shows up in everyday life.

Historical temperature records

Convert old temperature readings from Réaumur to Celsius for research or genealogy.

Example: A diary entry says 30°Ré, which is 37.5°C.

Old recipes

Some vintage recipes specify oven temperatures in Réaumur; convert to Celsius for modern cooking.

Example: A recipe calls for 25°Ré, which is 31.25°C.

Educational purposes

Learn about historical temperature scales and their relationships.

Example: Understand why water boils at 80°Ré.

Tips and common mistakes

Tips

  • Remember that 0°Ré is the freezing point of water, and 80°Ré is the boiling point.
  • For quick mental conversion, multiply Réaumur by 1.25 or add 25% of the value.
  • Use the calculator for precise conversions, especially for negative temperatures.

Common Mistakes to Avoid

  • Forgetting that the Réaumur scale has 80 degrees between freezing and boiling, not 100.
  • Using the wrong conversion factor, such as 1.8 (which is for Fahrenheit).
  • 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.