Convert Kelvin to Rankine
Convert kelvins to degrees rankine instantly. 1 K = 1.8 °R — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Rankine to Kelvin converter for the reverse conversion.
Units explained
Kelvin
The kelvin (K) is the SI base unit of thermodynamic temperature, defined by fixing the Boltzmann constant k at exactly 1.380649×10⁻²³ J/K. Zero kelvin is absolute zero, the lowest temperature physically possible, and kelvin values are written without a degree sign.
Named for William Thomson, 1st Baron Kelvin, who in 1848 calculated the value of absolute zero (about −273 °C) and proposed an absolute thermodynamic scale. His title comes from the River Kelvin, which flows past the University of Glasgow in Scotland.
The universal temperature unit of science and engineering — physics, chemistry, astronomy, and materials science — and the standard for color temperature in photography, displays, and lighting (a 5600 K daylight bulb).
Proposed by William Thomson (Lord Kelvin) in 1848; adopted as an SI base unit by the 10th CGPM in 1954 and redefined through the fixed Boltzmann constant by the 26th CGPM, effective May 20, 2019.
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.
Kelvin to Rankine conversion formula
The exact relationship between kelvins and degrees rankine:
To convert kelvins to degrees rankine, multiply the value in kelvins by 9/5. To reverse, multiply the value in degrees rankine by 5/9.
Both units count upward from absolute zero, so 0 K = 0 °R and the relationship is a pure ratio.
How to use this converter
Type a value into the calculator. The result in degrees rankine updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Rankine to Kelvin converter for the reverse direction.
Step-by-step: convert kelvins to degrees rankine
- Write down the temperature in kelvins (K).
- Multiply the value in kelvins by 9/5.
- The result is the same temperature expressed in degrees rankine (°R).
- To reverse, multiply the value in degrees rankine by 5/9 — or open the Rankine to Kelvin converter.
Worked examples
Example 1 — Convert 310.15 K to °R (human body temperature):
310.15 × 9/5 = 558.27 °R
Example 2 — Convert 373.15 K to °R (the boiling point of water):
373.15 × 9/5 = 671.67 °R
Kelvin to Rankine conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from kelvins to degrees rankine:
| Kelvin [K] | Rankine [°R] | Reference point |
|---|---|---|
| 0 | 0 | Absolute zero |
| 233.15 | 419.67 | Where Celsius and Fahrenheit coincide (−40°) |
| 255.3722222222 | 459.67 | Zero Fahrenheit (0 °F) |
| 273.15 | 491.67 | Water freezes (0 °C / 32 °F) |
| 273.16 | 491.688 | Triple point of water |
| 283.15 | 509.67 | Cool day (10 °C / 50 °F) |
| 293.15 | 527.67 | Room temperature (20 °C / 68 °F) |
| 298.15 | 536.67 | Standard laboratory temperature (25 °C) |
| 303.15 | 545.67 | Hot day (30 °C / 86 °F) |
| 310.15 | 558.27 | Human body temperature (37 °C / 98.6 °F) |
| 313.15 | 563.67 | Heat-wave day (40 °C / 104 °F) |
| 323.15 | 581.67 | Hot tap water (50 °C / 122 °F) |
| 373.15 | 671.67 | Water boils (100 °C / 212 °F) |
| 453.15 | 815.67 | Moderate baking oven (180 °C / 356 °F) |
| 5778 | 10400.4 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
How many degrees rankine is 1 kelvin?
How do I convert kelvins to degrees rankine?
How do I convert degrees rankine back to kelvins?
How many degrees rankine is 373.15 kelvins?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (1 K = 1.8 °R) 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.