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To Celsius: °C = °Ré × 5/4. To Fahrenheit: °F = °Ré × 9/4 + 32. To Kelvin: K = °Ré × 5/4 + 273.15.
1 °Ré = 1.25 °C. The Réaumur scale divides the freezing-to-boiling range of water into 80 degrees instead of 100.
For example, 1 Réaumur (°Ré) = 493.92 Rankine (°R).
| Réaumur (°Ré) | Rankine (°R) |
|---|---|
| 0.1 | 491.895 |
| 0.5 | 492.795 |
| 1 | 493.92 |
| 2 | 496.17 |
| 5 | 502.92 |
| 10 | 514.17 |
| 25 | 547.92 |
| 50 | 604.17 |
| 100 | 716.67 |
| 500 | 1616.67 |
| 1000 | 2741.67 |
The degree Réaumur is a historical temperature scale where water freezes at 0 °Ré and boils at 80 °Ré at standard pressure.
1 °Ré = 1.25 °C. The Réaumur scale divides the freezing-to-boiling range of water into 80 degrees instead of 100.
To Celsius: °C = °Ré × 5/4. To Fahrenheit: °F = °Ré × 9/4 + 32. To Kelvin: K = °Ré × 5/4 + 273.15.
Some traditional Italian pasta and cheese production references still mention Réaumur temperatures from historical recipes.
Réaumur used an alcohol-based thermometer, not mercury. Russia used the Réaumur scale as its standard until the early 20th century.
Confusing °Ré with °R (Rankine) — they are entirely different scales. Always use the full abbreviation °Ré.
Think of Réaumur as 'Celsius with 80 divisions instead of 100.' Multiply Réaumur by 1.25 to get Celsius.
The degree Rankine is an absolute temperature scale using the Fahrenheit degree size, where 0 °R equals absolute zero (−459.67 °F).
°R = °F + 459.67. The Rankine scale is to Fahrenheit what Kelvin is to Celsius. Same degree size as Fahrenheit.
To Fahrenheit: °F = °R − 459.67. To Celsius: °C = (°R − 491.67) × 5/9. To Kelvin: K = °R × 5/9.
US engineering thermodynamics calculations, gas turbine design, and some aerospace engineering applications.
Water freezes at 491.67 °R and boils at 671.67 °R. The Rankine scale is one of the four main temperature scales still in use.
Confusing Rankine with Réaumur — both use 'R' but are completely different scales. Use °R vs. °Ré to distinguish.
Rankine is to Fahrenheit as Kelvin is to Celsius. Both absolute scales start at 0 = absolute zero, just with different degree sizes.



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