This converter changes degrees Fahrenheit into degrees Réaumur. Temperature is the one conversion people most often get wrong, because the two scales differ in both the size of a degree and where zero sits, so a single multiplication is not enough.
The US domestic scale, placing water’s freezing point at 32 °F and its boiling point at 212 °F. An 18th-century scale with water freezing at 0 °Ré and boiling at 80 °Ré; it survives in some cheese and syrup making.
The correct relationship is °Ré = (°F − 32) × 0.444444. Enter any value — including negative ones — and the result updates immediately, with the reverse conversion shown underneath as a check.
The formula
°F- Your temperature in degrees Fahrenheit
32- The zero-point offset of the degrees Fahrenheit scale
0.444444- The ratio of degree sizes between the two scales
°Ré- The converted temperature in degrees Réaumur
How it works, step by step
- Enter the temperature in degrees Fahrenheit.
- The scale offset of 32 is removed first.
- The result is scaled by 0.444444 to match the size of a degree Réaumur.
- The degrees Réaumur offset of 0 is added to land on the final value.
Worked examples
Room temperature (20 °F)
Applying °Ré = (°F − 32) × 0.444444 to 20 °F gives -5.33 °Ré. This is the value most thermostats sit near.
Body temperature (37 °F)
37 °F converts to 2.22 °Ré. Normal human body temperature is often quoted as this figure.
How to read your score
Frequently asked questions
What is the formula to convert degrees Fahrenheit to degrees Réaumur?
°Ré = (°F − 32) × 0.444444. Unlike most unit conversions this one is not a single multiplication, because the two scales have different zero points as well as different degree sizes.
What is 0 °F in degrees Réaumur?
0 °F equals -14.22 °Ré.
What is 100 °F in degrees Réaumur?
100 °F equals 30.22 °Ré.
Why can I not just multiply by a single factor?
Because both scales are offset from each other. A factor alone works only when both scales share a zero point, which is true for kelvin and Rankine but not for Celsius and Fahrenheit. Skipping the offset is the most common source of wrong answers.
Is there a temperature where degrees Fahrenheit and degrees Réaumur read the same?
Yes — the two scales cross at 25.60 °F.
What is a degree Fahrenheit?
The US domestic scale, placing water’s freezing point at 32 °F and its boiling point at 212 °F.
What is a degree Réaumur?
An 18th-century scale with water freezing at 0 °Ré and boiling at 80 °Ré; it survives in some cheese and syrup making.
Degrees Fahrenheit to degrees Réaumur reference table
| Degrees Fahrenheit | Degrees Réaumur |
|---|---|
| -40 °F | -32.00 °Ré |
| -20 °F | -23.11 °Ré |
| -10 °F | -18.67 °Ré |
| 0 °F | -14.22 °Ré |
| 10 °F | -9.78 °Ré |
| 20 °F | -5.33 °Ré |
| 25 °F | -3.11 °Ré |
| 30 °F | -0.89 °Ré |
| 37 °F | 2.22 °Ré |
| 50 °F | 8.00 °Ré |
| 75 °F | 19.11 °Ré |
| 100 °F | 30.22 °Ré |
| 200 °F | 74.67 °Ré |
Includes the reference points that matter: water freezing and boiling, body temperature, and room temperature.