Convert Microkelvin to Rømer
Convert microkelvins to degrees rømer instantly. °Rø = (µK × 5.25e-7) − 135.90375 — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Rømer to Microkelvin converter for the reverse conversion.
Units explained
Microkelvin
One microkelvin (µK) is one millionth of a kelvin (10⁻⁶ K) above absolute zero.
Formed with the SI prefix 'micro-' (from Greek 'mikros', small) applied to the kelvin base unit.
Ultracold atomic physics — laser-cooled atom clouds and the atomic-fountain clocks that keep world time operate at microkelvin temperatures.
The micro- prefix entered metric usage with the 1873 British Association system and was formally adopted into the SI in 1960.
Rømer
The degree Rømer (°Rø) sets the freezing point of water at 7.5 °Rø and the boiling point at 60 °Rø; one degree Rømer equals exactly 40/21 of a kelvin (about 1.905 K).
Created by Danish astronomer Ole Rømer — famous for making the first quantitative measurement of the speed of light — who set 0 °Rø at the temperature of a salt-ice brine and 60 °Rø at boiling water.
Of historical rather than practical importance: it is remembered as the direct ancestor of the Fahrenheit scale and appears mainly in the history of science and in metrology coursework.
Devised by Ole Rømer in Copenhagen, Denmark, in 1701; Daniel Fahrenheit visited Rømer in 1708 and adapted this scale into his own.
Microkelvin to Rømer conversion formula
The exact relationship between microkelvins and degrees rømer:
To convert microkelvins to degrees rømer, multiply the value by 5.25e-7, then subtract 135.90375. To reverse, multiply the value by 1904761.905, then add 2.588643e+8.
Reference anchors: water freezes at 2.7315e+8 µK = 7.5 °Rø and boils at 3.7315e+8 µK = 60 °Rø (at standard atmospheric pressure).
How to use this converter
Type a value into the calculator. The result in degrees rømer updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Rømer to Microkelvin converter for the reverse direction.
Step-by-step: convert microkelvins to degrees rømer
- Write down the temperature in microkelvins (µK).
- Multiply the value by 5.25e-7, then subtract 135.90375.
- The result is the same temperature expressed in degrees rømer (°Rø).
- To reverse, multiply the value by 1904761.905, then add 2.588643e+8 — or open the Rømer to Microkelvin converter.
Worked examples
Example 1 — Convert 1 µK to °Rø:
(1 × 5.25e-7) − 135.90375 = -135.903749475 °Rø
Example 2 — Convert 100 µK to °Rø:
(100 × 5.25e-7) − 135.90375 = -135.9036975 °Rø
Microkelvin to Rømer conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from microkelvins to degrees rømer:
| Microkelvin [µK] | Rømer [°Rø] | Reference point |
|---|---|---|
| 0 | -135.90375 | Absolute zero |
| 2.3315e+8 | -13.5 | Where Celsius and Fahrenheit coincide (−40°) |
| 2.553722e+8 | -1.8333333333 | Zero Fahrenheit (0 °F) |
| 2.7315e+8 | 7.5 | Water freezes (0 °C / 32 °F) |
| 2.7316e+8 | 7.50525 | Triple point of water |
| 2.8315e+8 | 12.75 | Cool day (10 °C / 50 °F) |
| 2.9315e+8 | 18 | Room temperature (20 °C / 68 °F) |
| 2.9815e+8 | 20.625 | Standard laboratory temperature (25 °C) |
| 3.0315e+8 | 23.25 | Hot day (30 °C / 86 °F) |
| 3.1015e+8 | 26.925 | Human body temperature (37 °C / 98.6 °F) |
| 3.1315e+8 | 28.5 | Heat-wave day (40 °C / 104 °F) |
| 3.2315e+8 | 33.75 | Hot tap water (50 °C / 122 °F) |
| 3.7315e+8 | 60 | Water boils (100 °C / 212 °F) |
| 4.5315e+8 | 102 | Moderate baking oven (180 °C / 356 °F) |
| 5.778e+9 | 2897.54625 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
What is 1 µK in °Rø?
How do I convert microkelvins to degrees rømer?
How do I convert degrees rømer back to microkelvins?
At what temperature do the Microkelvin and Rømer scales read the same number?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (°Rø = (µK × 5.25e-7) − 135.90375) 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.