How many degrees Celsius are in 1 Réaumur?

There are exactly 1.25 degrees Celsius in 1 Réaumur. This means the conversion factor from Réaumur to Celsius is 1.25.

What is the formula to convert Réaumur to Celsius?

The formula to convert Réaumur to Celsius is: °C = °Ré × 5/4. For example, to convert 10 Réaumurs to degrees Celsius, you would multiply 10 by 1.25.

What are the common uses of Réaumur?

The Réaumur is commonly used in historic recipes, history of science.

How do you convert Réaumur to Celsius?

To convert Réaumurs to degrees Celsius, multiply by 1.25 (or divide by 0.8). Therefore, 1 Réaumur (°Ré) equals 1.25 degrees Celsius (°C).

1 °Ré = 1.25 °C — Réaumur to Celsius

Worked example: converting Réaumur to Celsius

Step 1 — start with the formula. °C = °Ré × 5/4
Step 2 — substitute your figure. 10 °Ré × 1.25
Step 3 — read the result. 10 °Ré = 12.5 °C
Step 4 — check it in reverse. °Ré = °C × 4/5 returns 10 °Ré, which matches the figure you started with.

Temperature Converter

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Decimals:

From

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1.25

1 °Ré = 1.25 °C

Formula:

°C = °Ré × 5/4

With your value: 1 °Ré = 1.25 °C

Other Réaumur to Celsius conversions

2 °Ré to °C 3 °Ré to °C 4 °Ré to °C 5 °Ré to °C 6 °Ré to °C 7 °Ré to °C 8 °Ré to °C

Réaumur to Celsius Conversion Table

Réaumur (°Ré)	Celsius (°C)
0.5	0.625
1	1.25
2	2.5
5	6.25
10	12.5
15	18.75
20	25
25	31.25
50	62.5
100	125
250	312.5
500	625
1000	1,250

Celsius to Réaumur Conversion Table

Celsius (°C)	Réaumur (°Ré)
0.5	0.4
1	0.8
2	1.6
5	4
10	8
15	12
20	16
25	20
50	40
100	80
250	200
500	400
1000	800

Where these values come from

Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.

Réaumur (°Ré)

Temperature

SI definition

Traceable to the kelvin, defined by fixing the Boltzmann constant at 1.380 649 × 10⁻²³ J/K. Celsius and Fahrenheit are exact affine transforms of the kelvin scale.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

Celsius (°C)

Temperature

SI definition

t/°C = T/K − 273.15. The degree Celsius has exactly the same magnitude as the kelvin.

Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)

Bureau International des Poids et Mesures · Reviewed 2026-07-01

How to Convert Réaumur to Celsius

To convert from Réaumur (°Ré) to Celsius (°C), multiply the value by 1.25.

Formula: °C = °Ré × 5/4

Reverse: °Ré = °C × 4/5

Step-by-Step Example

Start with your value in Réaumur. For example: 5 °Ré
Multiply by the conversion factor: 5 x 1.25
The result is: 6.25 °C

Réaumur and Celsius Relationship

This calculation facilitates standardized conversion between recognized units of temperature. Since 1 Réaumur equals approximately 1.25 degrees Celsius, the Réaumur represents a larger unit interval than the Celsius. Understanding the relationship between Réaumur and Celsius is essential for accurate calculations in physics, engineering, commerce, and daily applications.

About Réaumur

The Réaumur scale sets water's freezing point at 0 °Ré and its boiling point at 80 °Ré. It survives in a few European cheese and syrup recipes.

Common uses of Réaumur: historic recipes, history of science.

About Celsius

The Celsius scale sets 0°C as the freezing point and 100°C as the boiling point of water at standard pressure. It is used by most countries worldwide.

Fun Fact: Anders Celsius originally proposed a scale where 100° was freezing and 0° was boiling—it was later reversed!

Common uses of Celsius: weather, cooking, science.

Frequently Asked Questions

How many degrees Celsius are in 1 Réaumur?: There are exactly 1.25 degrees Celsius in 1 Réaumur. This means the conversion factor from Réaumur to Celsius is 1.25.
What is the formula to convert Réaumur to Celsius?: The formula to convert Réaumur to Celsius is: °C = °Ré × 5/4. For example, to convert 10 Réaumurs to degrees Celsius, you would multiply 10 by 1.25.
What is a Réaumur?: The Réaumur scale sets water's freezing point at 0 °Ré and its boiling point at 80 °Ré. It survives in a few European cheese and syrup recipes.
What is a Celsius?: The Celsius scale sets 0°C as the freezing point and 100°C as the boiling point of water at standard pressure. It is used by most countries worldwide.
What are the common uses of Réaumur?: The Réaumur is commonly used in historic recipes, history of science.

Réaumur to Celsius Converter

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