Convert Kelvin to Réaumur
Kelvin (K) to Réaumur (°Ré) temperature conversion — enter any value below for an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1K = -217.72°Ré
Water's freezing and boiling points, for reference
Freezing point
273.15K / 0°Ré
Boiling point
373.15K / 80°Ré
Conversion chart: Kelvin to Réaumur
Conversion table
| Kelvin (K) | Réaumur (°Ré) |
|---|---|
| 0.01 K | -218.512 °Ré |
| 0.1 K | -218.44 °Ré |
| 1 K | -217.72 °Ré |
| 2 K | -216.92 °Ré |
| 3 K | -216.12 °Ré |
| 5 K | -214.52 °Ré |
| 10 K | -210.52 °Ré |
| 20 K | -202.52 °Ré |
| 50 K | -178.52 °Ré |
| 100 K | -138.52 °Ré |
| 1000 K | 581.48 °Ré |
Kelvin (K)
Definition: The SI base unit of thermodynamic temperature. 0 K is absolute zero — the theoretical point at which molecular motion stops — and each Kelvin degree is the same size as a Celsius degree, just offset by 273.15.
History: Introduced by physicist William Thomson (later Lord Kelvin) in 1848, building on the concept of absolute zero derived from the behavior of gases as they cool.
Current use: Used throughout physics, chemistry, and engineering wherever an absolute, always-positive temperature scale is required, such as in gas law and blackbody radiation calculations.
Réaumur (°Ré)
Definition: A scale on which water freezes at 0° and boils at 80° under standard atmospheric pressure.
History: Introduced by French scientist René Antoine Ferchault de Réaumur in 1730. It was widely used across continental Europe — particularly France, Germany, and Russia — until the Celsius scale displaced it during the 19th century.
Current use: Largely obsolete today, though it still turns up occasionally in traditional European food-processing recipes, such as some cheese-making and sugar-syrup instructions.
Supported Scales
| Scale | Symbol | Water Freezes | Water Boils |
|---|---|---|---|
| Celsius | °C | 0°C | 100°C |
| Fahrenheit | °F | 32°F | 212°F |
| Kelvin | K | 273.15K | 373.15K |
| Rankine | °R | 491.67°R | 671.67°R |
| Réaumur | °Ré | 0°Ré | 80°Ré |
About These Parameters
- Value
- The temperature reading you want to convert, in the "From" scale. Negative values are accepted.
- From Unit
- The scale your input value is currently measured in.
- To Unit
- The scale you want the result converted into. Use the swap button to flip From and To instantly.
How Temperature Conversion Works
The Formula
Because each scale has a different zero point, conversion needs both a scale factor and an offset, not just a multiplier. The three most common formulas:
°F = °C × 9/5 + 32 K = °C + 273.15 °C = (°F − 32) × 5/9
For Kelvin → Réaumur: 1K converts to -217.72°Ré. Every conversion on this page routes through Celsius internally, then applies the target scale's own offset and factor.
Why Temperature Isn't a Simple Ratio
Length and weight conversions are pure multiplications because both scales share the same zero point (nothing weighs "negative zero"). Temperature scales don't: 0°C is water's freezing point, not the absence of heat, so "twice as hot" in Celsius doesn't mean "twice as hot" in Fahrenheit. Only Kelvin and Rankine start at true absolute zero, which is why they're used for scientific calculations involving ratios of temperature.
Absolute Zero
Absolute zero — 0 K, −273.15°C, −459.67°F, 0°R — is the coldest possible temperature, the point at which atoms have minimum possible thermal motion. It has never been reached experimentally, though physicists have cooled matter to within a fraction of a billionth of a degree above it.
Example
1K equals -217.72°Ré. For comparison, normal human body temperature (37°C) is 29.6°Ré — this value is 247.3°Ré cooler than body temperature.
Frequently Asked Questions
How many Réaumur are in 1 Kelvin?
1 Kelvin (K) equals exactly -217.72 Réaumur (°Ré).
Why does the US use Fahrenheit while most of the world uses Celsius?
The US inherited Fahrenheit from British colonial-era usage and never mandated a switch to Celsius, unlike the UK and most other countries, which adopted Celsius alongside broader metrication in the mid-20th century.
What's the difference between Kelvin and Celsius?
They use the same size degree — a 1 K change equals a 1°C change — but Kelvin starts at absolute zero (0 K = −273.15°C) instead of water's freezing point, so Kelvin values are never negative.
Is the Réaumur scale still used anywhere?
Rarely. It was common in 18th and 19th century Europe but was almost entirely replaced by Celsius; it occasionally survives in older European recipes, particularly some traditional cheese-making and confectionery instructions.