Instant · Precise · Universal
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To Fahrenheit: °F = °C × 9/5 + 32. To Kelvin: K = °C + 273.15. To Rankine: °R = (°C + 273.15) × 9/5.
°C = K − 273.15. The Celsius and Kelvin scales have identical degree sizes — they differ only by an offset of 273.15.
For example, 1 Celsius (°C) = 0.8 Réaumur (°Ré).
| Celsius (°C) | Réaumur (°Ré) |
|---|---|
| 0.1 | 0.08 |
| 0.5 | 0.4 |
| 1 | 0.8 |
| 2 | 1.6 |
| 5 | 4 |
| 10 | 8 |
| 25 | 20 |
| 50 | 40 |
| 100 | 80 |
| 500 | 400 |
| 1000 | 800 |
The degree Celsius is a unit of temperature on the Celsius scale, where 0 °C is the freezing point and 100 °C is the boiling point of water at standard atmospheric pressure.
°C = K − 273.15. The Celsius and Kelvin scales have identical degree sizes — they differ only by an offset of 273.15.
To Fahrenheit: °F = °C × 9/5 + 32. To Kelvin: K = °C + 273.15. To Rankine: °R = (°C + 273.15) × 9/5.
Weather reports, cooking temperatures, body temperature (37 °C normal), refrigerator settings (2–4 °C), and industrial processes.
−40 °C = −40 °F — the only point where Celsius and Fahrenheit scales intersect. The hottest recorded temperature on Earth was 56.7 °C in Death Valley.
Forgetting the °C × 9/5 + 32 offset when converting to Fahrenheit. Also, assuming 0 °C = 0 K (actually 0 °C = 273.15 K).
Key anchors: 0 °C = water freezes, 37 °C = body temp, 100 °C = water boils. For quick °C→°F: double and add 30 (approximate).
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.



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