# Rankine to Réaumur (°R to °Ré) Source: https://www.unitconvertercalculator.com/temperature/rankine-to-reaumur/ To convert Rankine to Reaumur, use the formula: Re = (R - 491.67) x 4/9. The Rankine scale is the absolute Fahrenheit scale used in US thermodynamic engineering, while the Reaumur scale is the historical European scale once standard in France and Germany. Water freezes at 491.67 degrees R (0 Re) and boils at 671.67 degrees R (80 Re). ## Formula °R via Kelvin to °Ré ## Conversion Table | Rankine (°R) | Réaumur (°Ré) | |---|---| | 0 °R | -218.52 °Ré | | 100 °R | -174.07555555556 °Ré | | 200 °R | -129.63111111111 °Ré | | 300 °R | -85.186666666664 °Ré | | 400 °R | -40.742222222224 °Ré | | 459 °R | -14.52 °Ré | | 491.67 °R | 0 °Ré | | 500 °R | 3.702222222224 °Ré | | 530 °R | 17.035555555552 °Ré | | 559 °R | 29.924444444448 °Ré | | 600 °R | 48.146666666664 °Ré | | 671.67 °R | 80 °Ré | | 700 °R | 92.591111111112 °Ré | | 800 °R | 137.03555555555 °Ré | | 1000 °R | 225.92444444445 °Ré | ## Units ### Rankine (°R) An absolute temperature scale using Fahrenheit-sized degrees. 0 °R equals absolute zero. Used in some US engineering applications, especially thermodynamics. ### Réaumur (°Ré) A historical temperature scale where water freezes at 0 °Ré and boils at 80 °Ré. Named after René Antoine Ferchault de Réaumur. Once widely used in Europe. ## Background The Rankine scale was created by William Rankine, 1859, used in American aerospace and chemical engineering. The Reaumur scale was created by Rene Antoine Ferchault de Reaumur, 1730, once widespread in continental Europe. Converting between them bridges different eras and different measurement philosophies in the history of thermometry. ## Good to Know The history of temperature measurement is the history of scientific collaboration and competition across borders. The Rankine scale (used in American aerospace and chemical engineering) and the Reaumur scale (once widespread in continental Europe) represent different national contributions to solving the same fundamental problem: how to assign numbers to the sensation of hot and cold. ## FAQ ### How do you convert Rankine to Reaumur? Use the formula Re = (R - 491.67) x 4/9. At the freezing point of water: 491.67 R = 0 Re. At the boiling point: 671.67 R = 80 Re. ### When would you need to convert Rankine to Reaumur? This conversion is needed when interpreting historical scientific records, comparing temperature data across different measurement traditions, or completing engineering calculations that mix temperature scales from different national standards. ### What are the key reference points for both scales? Water freezes at 491.67 R = 0 Re. Water boils at 671.67 R = 80 Re. These two fixed points anchor both scales and provide easy verification of any conversion calculation. ## Non-Frequently Asked Questions ### Is the Rankine-to-Reaumur conversion a meeting of two ghosts? Rankine is the ghost of American engineering past (still occasionally seen in thermodynamic calculations). Reaumur is the ghost of European culinary past (still occasionally seen in cheese-making references). Their conversion is a handshake between two apparitions from different measurement traditions, neither fully alive nor fully dead. ### At what Rankine temperature does a French baker's oven operate? A typical bread-baking oven at 230 degrees Celsius (184 degrees Reaumur) operates at about 905 degrees Rankine. Expressing French baking temperatures in American engineering units produces numbers that sound like rocket engine exhaust. Both numbers describe the same perfectly ordinary oven, proving that temperature is universal even when its expression is culture-specific. ### Would converting Rankine to Reaumur ever help anyone? It is difficult to construct a realistic scenario. American thermodynamic engineers (Rankine users) and European food artisans (historical Reaumur users) occupy entirely non-overlapping professional domains. The conversion exists for mathematical completeness, not for solving anyone's actual problem. 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