Convert Rankine to Millikelvin
Convert degrees rankine to millikelvins instantly. 1 °R = 555.5555555556 mK — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Millikelvin 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.
Millikelvin
One millikelvin (mK) is one thousandth of a kelvin (10⁻³ K), measured upward from absolute zero.
Formed with the SI prefix 'milli-' (from Latin 'mille', a thousand) applied to the kelvin base unit.
Cryogenics and low-temperature physics — the dilution refrigerators that cool superconducting quantum computers operate at roughly 10–20 mK.
The milli- prefix belongs to the original metric system of 1795 and was carried into the SI in 1960; the kelvin became an SI base unit in 1954.
Rankine to Millikelvin conversion formula
The exact relationship between degrees rankine and millikelvins:
To convert degrees rankine to millikelvins, multiply the value in degrees rankine by 555.5555556. To reverse, multiply the value in millikelvins by 0.0018.
Both units count upward from absolute zero, so 0 °R = 0 mK and the relationship is a pure ratio.
How to use this converter
Type a value into the calculator. The result in millikelvins updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Millikelvin to Rankine converter for the reverse direction.
Step-by-step: convert degrees rankine to millikelvins
- Write down the temperature in degrees rankine (°R).
- Multiply the value in degrees rankine by 555.5555556.
- The result is the same temperature expressed in millikelvins (mK).
- To reverse, multiply the value in millikelvins by 0.0018 — or open the Millikelvin to Rankine converter.
Worked examples
Example 1 — Convert 1 °R to mK:
1 × 555.5555556 = 555.5555555556 mK
Example 2 — Convert 100 °R to mK:
100 × 555.5555556 = 55555.5555555556 mK
Rankine to Millikelvin conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from degrees rankine to millikelvins:
| Rankine [°R] | Millikelvin [mK] | Reference point |
|---|---|---|
| 0 | 0 | Absolute zero |
| 419.67 | 233150 | Where Celsius and Fahrenheit coincide (−40°) |
| 459.67 | 255372.2222222222 | Zero Fahrenheit (0 °F) |
| 491.67 | 273150 | Water freezes (0 °C / 32 °F) |
| 491.688 | 273160 | Triple point of water |
| 509.67 | 283150 | Cool day (10 °C / 50 °F) |
| 527.67 | 293150 | Room temperature (20 °C / 68 °F) |
| 536.67 | 298150 | Standard laboratory temperature (25 °C) |
| 545.67 | 303150 | Hot day (30 °C / 86 °F) |
| 558.27 | 310150 | Human body temperature (37 °C / 98.6 °F) |
| 563.67 | 313150 | Heat-wave day (40 °C / 104 °F) |
| 581.67 | 323150 | Hot tap water (50 °C / 122 °F) |
| 671.67 | 373150 | Water boils (100 °C / 212 °F) |
| 815.67 | 453150 | Moderate baking oven (180 °C / 356 °F) |
| 10400.4 | 5778000 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
How many millikelvins is 1 degree rankine?
How do I convert degrees rankine to millikelvins?
How do I convert millikelvins back to degrees rankine?
How many millikelvins is 100 degrees rankine?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (1 °R = 555.5555555556 mK) 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.