Instant · Precise · Universal
6 units available
6 categories total
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) = 125 Triple Point of Water (Tₜ).
| Réaumur (°Ré) | Triple Point of Water (Tₜ) |
|---|---|
| 0.1 | 12.5 |
| 0.5 | 62.5 |
| 1 | 125 |
| 2 | 250 |
| 5 | 625 |
| 10 | 1250 |
| 25 | 3125 |
| 50 | 6250 |
| 100 | 12500 |
| 500 | 62500 |
| 1000 | 125000 |
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.
A unit based on the triple point of water — the unique temperature and pressure at which water coexists as solid, liquid, and gas simultaneously (0.01 °C / 273.16 K).
1 Tₜ = 0.01 °C = 273.16 K. The triple point is a fixed thermodynamic state, not dependent on pressure corrections.
To Celsius: °C = Tₜ × 0.01. To Kelvin: K = Tₜ × 0.01 + 273.15.
Calibrating precision thermometers, validating temperature measurement systems, and establishing traceability in national labs.
The triple point of water requires extreme purity — even tiny impurities shift the temperature. It occurs at 611.657 Pa pressure, much lower than atmospheric.
Confusing the triple point (0.01 °C) with the normal freezing point (0 °C). The difference is tiny but critical in precision metrology.
The triple point is where all three phases coexist. It's a unique, reproducible temperature — that's why it was perfect for defining the kelvin.



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