Convert Kelvin to Reaumur - Temperature Converter
This tool converts a temperature value given in Kelvin (K) to the Réaumur scale (°Ré). The mathematical relationship between these scales is exact; the tool performs the fixed arithmetic conversion and returns the corresponding Réaumur temperature.
Use this converter for quick unit conversions, verification of calculations, or integration into workflows that require Réaumur values. Note that while the numerical conversion is exact, real-world thermometer readings carry measurement uncertainty and potential bias; read the methodology and FAQs for guidance on calibration and accuracy.
Interactive Converter
Convert between kelvin and reaumur with precision rounding.
Quick reference table
| Kelvin | Reaumur |
|---|---|
| 1 K | -217.72 °Ré |
| 5 K | -214.52 °Ré |
| 10 K | -210.52 °Ré |
| 25 K | -198.52 °Ré |
| 50 K | -178.52 °Ré |
| 100 K | -138.52 °Ré |
Methodology
The conversion uses the defined relationships between Kelvin, Celsius, and Réaumur. Kelvin is an absolute thermodynamic scale where 0 K is absolute zero. Réaumur is a historic scale linked to the Celsius scale by a simple linear factor.
Mathematically the conversion is exact and requires no empirical coefficients. However, when converting measured temperatures (from sensors or instruments) you should account for instrument uncertainty, calibration status, and environmental effects. For traceable measurements, follow calibration and uncertainty practices described by NIST, ISO/IEC 17025, and relevant instrument manufacturer guidance.
Worked examples
Example 1: 273.15 K → (273.15 - 273.15) × 0.8 = 0.00 °Ré (freezing point of water).
Example 2: 373.15 K → (373.15 - 273.15) × 0.8 = 80.00 °Ré (boiling point of water at standard pressure).
Example 3: 300 K → (300 - 273.15) × 0.8 = 21.48 °Ré.
Further resources
External guidance
Expert Q&A
Is the conversion exact?
Yes. The mathematical relationship between Kelvin, Celsius, and Réaumur is exact: °Ré = (K - 273.15) × 4/5. Any numerical difference arises from rounding or from uncertainty in the original measured temperature.
Do I need to calibrate my thermometer before converting?
Calibrate instruments according to manufacturer recommendations and accepted standards if you need traceable measurements. Conversion does not remove sensor bias or drift. For traceability and documented uncertainty, use calibration services accredited to ISO/IEC 17025 or national metrology laboratories that provide references to NIST or equivalent.
How should I handle uncertainty?
Report the converted value together with the measurement uncertainty of the original Kelvin reading. Propagate uncertainty through the linear transformation (multiplying uncertainty by 0.8 for Celsius→Réaumur). For formal uncertainty analysis follow the Guide to the Expression of Uncertainty in Measurement (GUM) and relevant NIST/ISO guidance.
Are Réaumur temperatures used in modern practice?
Réaumur is largely historical and rarely used in modern scientific or industrial practice, where Celsius and Kelvin dominate. Use Réaumur only where legacy documents or local conventions require it, and ensure units and tolerances are clearly stated.
Sources & citations
- NIST - Temperature and Thermometry — https://www.nist.gov/pml/thermometry
- ISO/IEC 17025 - General requirements for the competence of testing and calibration laboratories — https://www.iso.org/standard/66912.html
- BIPM - The International System of Units (SI Brochure) — https://www.bipm.org/en/publications/si-brochure
- OSHA - Heat Illness Prevention and Workplace Temperature Guidance — https://www.osha.gov/heat-exposure
- Guide to the Expression of Uncertainty in Measurement (GUM) — https://www.bipm.org/en/publications/guides