Reaumur is a historical temperature scale.
Reaumurs to Celsius Converter — Re to C
Convert Reaumur (Re) to Celsius (C) using the exact temperature formula. See the formula, worked examples, conversion table, history, and common uses.
Reaumurs to Celsius converter
Converter
Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Reaumur, and Romer.
Context values
Some unit families need one extra value for a physically accurate result.
Celsius is a temperature scale with water freezing at 0 C and boiling at 100 C.
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
Temperature conversion uses Kelvin as the intermediate absolute scale.
Reserved above the conversion cards and below the converter.
About Converting Reaumurs to Celsius
Celsius is a widely used everyday temperature scale, while Reaumur is a historical temperature scale no longer in common use — this conversion is mainly useful for historical reference or comparing older scientific texts against modern figures.
Formula
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
Both scales are converted through Kelvin as a common absolute reference point.
Simple example
(0 − 32) × 5/9 = 0 °C
0 reaumurs = 0 celsius.
Real-world example
(0 − 32) × 5/9 = 0 °C
0 reaumurs = 0 celsius.
Conversion table
| Reaumur (Re) | Celsius (C) |
|---|---|
| -40 Re | -50 C |
| -20 Re | -25 C |
| 0 Re | 0 C |
| 20 Re | 25 C |
| 37 Re | 46.25 C |
| 100 Re | 125 C |
Reverse conversion: Celsius to Reaumur
(1.25 × 9/5) + 32 = 1 °F
1.25 celsius = 1 reaumur.
Convert the source temperature to Kelvin, then convert Kelvin to the target scale.
For a page dedicated to this direction, see Celsius to Reaumur.
Understanding the Reaumur (Re)
Reaumur is a historical temperature scale.
Understanding the Celsius
Celsius (C) measures temperature. Celsius is defined relative to the Kelvin scale, with 0 °C set at 273.15 K. It is classified as a SI-derived temperature scale.
Where it's used: Standard temperature scale in nearly every country except the United States
Uses of the Celsius today
- Weather forecasting and climate reporting worldwide
- Scientific and laboratory temperature measurement (alongside Kelvin)
- Cooking and food safety in most countries outside the US
History of the Celsius
Swedish astronomer Anders Celsius proposed a 100-point temperature scale in 1742, but his original scale ran in the opposite direction, with 0° at water's boiling point and 100° at freezing.
The scale was reversed to its modern orientation shortly after his death, commonly attributed to instrument maker Daniel Ekström and naturalist Carl Linnaeus around 1744-1745.
The scale was renamed from 'centigrade' to 'Celsius' by international agreement in 1948, and it is now formally defined as the Kelvin scale shifted by 273.15, rather than independently by the freezing and boiling points of water.
Historical origin. Celsius was not the invention of a single named person; it developed through the process described above.
Celsius — sources
- BIPM SI Brochure — Celsius temperature scale — Formal definition tying Celsius to Kelvin.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many celsius are in 1 reaumur?
1 reaumur equals 1.25 celsius, using the offset temperature formula rather than an estimate.
How do I convert reaumur to celsius?
Use the formula shown above: it involves both a multiplication and an addition/subtraction because the two scales don't share a common zero point.
How do I convert celsius back to reaumur?
Use the reverse factor: 1 celsius equals 0.8 reaumurs. You can also use the swap control in the converter above to flip the direction instantly.
What is a reaumur?
Reaumur (Re) is a unit of temperature.
What is a celsius?
Celsius (C) measures temperature. Celsius is defined relative to the Kelvin scale, with 0 °C set at 273.15 K. It is classified as a SI-derived temperature scale.
Is the Reaumur to Celsius conversion exact?
Yes. Both scales are formally defined relative to the Kelvin scale, so the conversion formula is exact — the only rounding involved is in how many decimal places you choose to display.