Convert Rankine to Celsius (°R → °C)
The Rankine scale is the absolute version of Fahrenheit, used in American engineering thermodynamics calculations.
Rankine to Celsius Conversion Table
10 common values| Rankine | Celsius |
|---|---|
| -40 °R | -295.37222 °C |
| -20 °R | -284.26111 °C |
| 0 °R | -273.15 °C |
| 10 °R | -267.59444 °C |
| 20 °R | -262.03889 °C |
| 25 °R | -259.26111 °C |
| 30 °R | -256.48333 °C |
| 37 °R | -252.59444 °C |
| 100 °R | -217.59444 °C |
| 200 °R | -162.03889 °C |
How to Convert Rankine to Celsius Manually
Step by StepTemperature scales differ in both zero-point and degree size, so conversion uses a formula — not simple multiplication. Follow these steps to convert degrees Rankine to degrees Celsius by hand.
- 1Take your value in degrees RankineStart with the number of degrees Rankine (°R) you want to convert.
- 2Apply the formulaUse the formula:
°C = °R × 5/9 − 273.15 - 3Read the result in degrees CelsiusThe result is your value in degrees Celsius (°C).
Formula
Temperature conversion uses an offset formula, not simple multiplication.
°C = °R × 5/9 − 273.15°R = (°C + 273.15) × 9/5Tips
Use these in everyday conversions- °R = °F + 459.67.
- °R = K × 9/5. Identical absolute-zero anchor, different degree size.
- Rankine is essentially obsolete outside specific US engineering specialisms.
Common Mistakes
Avoid these- Confusing Rankine with Réaumur (another historical scale).
- Using Rankine outside US engineering contexts — nowhere else uses it.
- Writing °R when Réaumur degree is meant — Réaumur is obsolete.
About Rankine and Celsius
What is the Rankine?
The Rankine scale is the absolute version of Fahrenheit, named after Scottish engineer William John Macquorn Rankine (1820–1872). Like Kelvin, Rankine sets 0° at absolute zero, but uses Fahrenheit-sized degrees: 1°R = 1°F (in size, not in offset). Water freezes at 491.67°R and boils at 671.67°R at sea level. The scale is rarely used today except in some American engineering disciplines, particularly in older thermodynamics, refrigeration, and aerospace calculations where Fahrenheit is the working unit. The Rankine relates to Fahrenheit by °R = °F + 459.67 and to Kelvin by °R = K × 9/5. While Kelvin has largely replaced Rankine in modern science, Rankine retains a niche in certain US engineering textbooks and HVAC standards. Its main advantage is allowing absolute-temperature thermodynamic calculations within a Fahrenheit-based engineering context.
- US aerospace thermodynamics
- US steam-turbine and power-plant engineering
- Some US industrial combustion calculations
Room temperature ≈ 527 °R. Water boils at 671.67 °R. US rocket-engine thermodynamics textbooks use Rankine.
What is the Celsius?
Celsius is the global temperature scale used for weather forecasts, science, medicine, and daily life in all countries except the United States. Originally proposed by Swedish astronomer Anders Celsius in 1742 (with 0° as boiling and 100° as freezing — the inverse of today's scale), the modern version was reversed shortly after his death. Since 2019, Celsius has been redefined via the Kelvin scale: 0°C is exactly 273.15 K, and 1°C equals 1 K in size. Water freezes at 0°C, boils at 100°C at sea level, and human body temperature is around 37°C. Comfortable room temperature is about 20–22°C, and a hot summer day is 30–35°C. Celsius relates to Fahrenheit by the formula °F = °C × 9/5 + 32, and to Kelvin by adding 273.15. The scale's decimal-friendly division of water's phase transitions made it the natural metric choice.
- Daily weather forecasts worldwide (except US)
- Cooking temperatures in Europe, Asia, Latin America
- Body temperature on medical thermometers
Room temperature is about 20 °C. Normal body temperature is 37 °C. Typical fridge setting is 4 °C. European winter can reach −20 °C; desert summer 45+ °C.