Convert Microkelvin to Millikelvin
Convert microkelvins to millikelvins instantly. 1 µK = 0.001 mK — use the live calculator, the exact formula, a reference-temperature table and worked examples. Also check the Millikelvin 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.
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.
Microkelvin to Millikelvin conversion formula
The exact relationship between microkelvins and millikelvins:
To convert microkelvins to millikelvins, multiply the value in microkelvins by 1/1000. To reverse, multiply the value in millikelvins by 1000.
Both units count upward from absolute zero, so 0 µK = 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 Microkelvin converter for the reverse direction.
Step-by-step: convert microkelvins to millikelvins
- Write down the temperature in microkelvins (µK).
- Multiply the value in microkelvins by 1/1000.
- The result is the same temperature expressed in millikelvins (mK).
- To reverse, multiply the value in millikelvins by 1000 — or open the Millikelvin to Microkelvin converter.
Worked examples
Example 1 — Convert 1 µK to mK:
1 × 1/1000 = 0.001 mK
Example 2 — Convert 100 µK to mK:
100 × 1/1000 = 0.1 mK
Microkelvin to Millikelvin conversion table
Physically meaningful reference temperatures, from absolute zero to the surface of the Sun, converted from microkelvins to millikelvins:
| Microkelvin [µK] | Millikelvin [mK] | Reference point |
|---|---|---|
| 0 | 0 | Absolute zero |
| 2.3315e+8 | 233150 | Where Celsius and Fahrenheit coincide (−40°) |
| 2.553722e+8 | 255372.2222222222 | Zero Fahrenheit (0 °F) |
| 2.7315e+8 | 273150 | Water freezes (0 °C / 32 °F) |
| 2.7316e+8 | 273160 | Triple point of water |
| 2.8315e+8 | 283150 | Cool day (10 °C / 50 °F) |
| 2.9315e+8 | 293150 | Room temperature (20 °C / 68 °F) |
| 2.9815e+8 | 298150 | Standard laboratory temperature (25 °C) |
| 3.0315e+8 | 303150 | Hot day (30 °C / 86 °F) |
| 3.1015e+8 | 310150 | Human body temperature (37 °C / 98.6 °F) |
| 3.1315e+8 | 313150 | Heat-wave day (40 °C / 104 °F) |
| 3.2315e+8 | 323150 | Hot tap water (50 °C / 122 °F) |
| 3.7315e+8 | 373150 | Water boils (100 °C / 212 °F) |
| 4.5315e+8 | 453150 | Moderate baking oven (180 °C / 356 °F) |
| 5.778e+9 | 5778000 | Surface of the Sun (≈5,505 °C) |
Frequently asked questions
How many millikelvins is 1 microkelvin?
How do I convert microkelvins to millikelvins?
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How many millikelvins is 100 microkelvins?
Can a temperature be below absolute zero?
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Sources & references
Conversion relationship (1 µK = 0.001 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.