This converter changes degrees Réaumur into kelvin. 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.
An 18th-century scale with water freezing at 0 °Ré and boiling at 80 °Ré; it survives in some cheese and syrup making. The SI absolute scale, starting at absolute zero. Kelvin uses no degree sign and no negative values.
The correct relationship is K = °Ré × 1.25 + 273.15. Enter any value — including negative ones — and the result updates immediately, with the reverse conversion shown underneath as a check.
The formula
°Ré- Your temperature in degrees Réaumur
0- The zero-point offset of the degrees Réaumur scale
1.25- The ratio of degree sizes between the two scales
K- The converted temperature in kelvin
How it works, step by step
- Enter the temperature in degrees Réaumur.
- The scale offset of 0 is removed first.
- The result is scaled by 1.25 to match the size of a kelvin.
- The kelvin offset of 273.15 is added to land on the final value.
Worked examples
Room temperature (20 °Ré)
Applying K = °Ré × 1.25 + 273.15 to 20 °Ré gives 298.15 K. This is the value most thermostats sit near.
Body temperature (37 °Ré)
37 °Ré converts to 319.40 K. 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 Réaumur to kelvin?
K = °Ré × 1.25 + 273.15. 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 °Ré in kelvin?
0 °Ré equals 273.15 K.
What is 100 °Ré in kelvin?
100 °Ré equals 398.15 K.
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 Réaumur and kelvin read the same?
Yes — the two scales cross at 1092.60 °Ré.
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.
What is a kelvin?
The SI absolute scale, starting at absolute zero. Kelvin uses no degree sign and no negative values.
Degrees Réaumur to kelvin reference table
| Degrees Réaumur | Kelvin |
|---|---|
| -40 °Ré | 223.15 K |
| -20 °Ré | 248.15 K |
| -10 °Ré | 260.65 K |
| 0 °Ré | 273.15 K |
| 10 °Ré | 285.65 K |
| 20 °Ré | 298.15 K |
| 25 °Ré | 304.40 K |
| 30 °Ré | 310.65 K |
| 37 °Ré | 319.40 K |
| 50 °Ré | 335.65 K |
| 75 °Ré | 366.90 K |
| 100 °Ré | 398.15 K |
| 200 °Ré | 523.15 K |
Includes the reference points that matter: water freezing and boiling, body temperature, and room temperature.