Convert Rankine to Celsius
Convert degrees rankine to degrees celsius instantly. °C = (°R × 5/9) − 273.15 — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Celsius to Rankine converter for the reverse conversion.
Units explained
Rankine
The degree Rankine (°R) is the absolute counterpart of the Fahrenheit scale: 0 °R is absolute zero, and one degree Rankine is exactly the same size as one degree Fahrenheit (5/9 of a kelvin). Water freezes at 491.67 °R.
Named for William John Macquorn Rankine, the Scottish engineer and physicist who proposed an absolute scale built from Fahrenheit-sized degrees, paralleling Kelvin's absolute scale built from Celsius-sized degrees.
Used mainly in United States aerospace, thermodynamics, and power-plant engineering, where calculations demand absolute temperature but legacy data, instruments, and codes are in Fahrenheit.
Proposed by W. J. M. Rankine at the University of Glasgow in 1859, eleven years after Lord Kelvin's absolute scale of 1848.
Celsius
The degree Celsius (°C) is the SI's everyday temperature unit. One degree Celsius is exactly the same size as one kelvin, with the zero point shifted so that 0 °C = 273.15 K. Water freezes near 0 °C and boils near 100 °C at standard atmospheric pressure.
Named for Swedish astronomer Anders Celsius, who in 1742 proposed a 100-degree scale between the boiling and freezing points of water. His original scale ran in reverse (0 at boiling, 100 at freezing); it was inverted to the modern direction shortly after his death.
The world's standard everyday temperature scale, used in nearly every country — including throughout India — for weather forecasts, cooking, medicine, science classrooms, and industry.
Devised by Anders Celsius at Uppsala University, Sweden, in 1742; the inverted modern form was in use by 1745, and the name 'degree Celsius' replaced 'degree centigrade' internationally at the 9th CGPM in 1948.
Rankine to Celsius conversion formula
The exact relationship between degrees rankine and degrees celsius:
To convert degrees rankine to degrees celsius, multiply the value by 5/9, then subtract 273.15. To reverse, multiply the value by 9/5, then add 491.67.
Reference anchors: water freezes at 491.67 °R = 0 °C and boils at 671.67 °R = 100 °C (at standard atmospheric pressure).
How to use this converter
Type a value into the calculator. The result in degrees celsius updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Celsius to Rankine converter for the reverse direction.
Step-by-step: convert degrees rankine to degrees celsius
- Write down the temperature in degrees rankine (°R).
- Multiply the value by 5/9, then subtract 273.15.
- The result is the same temperature expressed in degrees celsius (°C).
- To reverse, multiply the value by 9/5, then add 491.67 — or open the Celsius to Rankine converter.
Worked examples
Example 1 — Convert 1 °R to °C:
(1 × 5/9) − 273.15 = -272.5944444444 °C
Example 2 — Convert 100 °R to °C:
(100 × 5/9) − 273.15 = -217.5944444444 °C
Rankine to Celsius conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from degrees rankine to degrees celsius:
| Rankine [°R] | Celsius [°C] | Reference point |
|---|---|---|
| 0 | -273.15 | Absolute zero |
| 419.67 | -40 | Where Celsius and Fahrenheit coincide (−40°) |
| 459.67 | -17.7777777778 | Zero Fahrenheit (0 °F) |
| 491.67 | 0 | Water freezes (0 °C / 32 °F) |
| 491.688 | 0.01 | Triple point of water |
| 509.67 | 10 | Cool day (10 °C / 50 °F) |
| 527.67 | 20 | Room temperature (20 °C / 68 °F) |
| 536.67 | 25 | Standard laboratory temperature (25 °C) |
| 545.67 | 30 | Hot day (30 °C / 86 °F) |
| 558.27 | 37 | Human body temperature (37 °C / 98.6 °F) |
| 563.67 | 40 | Heat-wave day (40 °C / 104 °F) |
| 581.67 | 50 | Hot tap water (50 °C / 122 °F) |
| 671.67 | 100 | Water boils (100 °C / 212 °F) |
| 815.67 | 180 | Moderate baking oven (180 °C / 356 °F) |
| 10400.4 | 5504.85 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
What is 1 °R in °C?
How do I convert degrees rankine to degrees celsius?
How do I convert degrees celsius back to degrees rankine?
At what temperature do the Rankine and Celsius scales read the same number?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (°C = (°R × 5/9) − 273.15) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- BIPM — International Temperature Scale of 1990 (ITS-90)
The internationally agreed practical temperature scale, defining fixed points (including the triple point of water at 273.16 K) and interpolation instruments used by national metrology institutes for thermometer calibration worldwide.
- CODATA Internationally Recommended Values of the Fundamental Physical Constants
Committee on Data of the International Science Council; authoritative source for the masses of fundamental particles (electron, proton, neutron) and the atomic mass constant.