1 kelvin = -272.15 °C
1 K = -272.15 °C · type math like (12*4)+6.5
Kelvin to Celsius turns absolute temperatures from physics papers, cryogenics specs or space missions into numbers people can picture. Students also need it to report gas-law answers in everyday units.
Space science publishes temperatures in kelvin. The average surface of Mars is about 210 K, which is −63 °C, while the day side of Mercury reaches about 700 K, or 427 °C. Converting makes these numbers easier to compare with Earth weather.
Superconductors are another example. Classic niobium–titanium magnets used in MRI machines operate near 4.2 K, the boiling point of liquid helium, which is −268.95 °C. The so-called high-temperature superconductors work at 77 K or higher, still −196 °C.
In computing, dilution refrigerators for quantum computers cool chips to about 0.015 K, which is −273.135 °C. At these extremes, Celsius figures all look nearly identical, which is why physicists prefer kelvin.
Meteorology and climate models output temperatures in kelvin internally. A surface temperature of 288 K, often used as Earth's global average, is 14.85 °C. Climate scientists usually convert back to Celsius when presenting results to the public.
Thermal cameras and infrared sensors can report values in kelvin. A reading of 310 K corresponds to 36.85 °C.
Refrigeration engineers also use kelvin when calculating efficiency. A fridge with an inside temperature of 277 K and a room at 295 K has a temperature difference of 18 K, which is the same as 18 °C.
Laboratory freezers at −80 °C are at 193.15 K, and liquid helium at 4.2 K is −268.95 °C.
Star colours depend on surface temperature in kelvin. Red dwarfs are around 3,000 K, which is 2,727 °C, while hot blue stars exceed 20,000 K.
A quick check: everyday temperatures sit between about 250 K and 320 K, which is −23 °C to 47 °C. If you convert a room-temperature sample and get a Celsius value in the hundreds, you added instead of subtracted. Any kelvin value below 273.15 will be negative in Celsius, and 0 K is the absolute floor at −273.15 °C.
°C = K − 273.15
Reverse: 1 °C = 274.15 K.
Convert 77 K, the boiling point of liquid nitrogen, to Celsius.
Answer: 77 K = −196.15 °C.
| K | °C |
|---|---|
| 1 K | -272.15 °C |
| 2 K | -271.15 °C |
| 3 K | -270.15 °C |
| 4 K | -269.15 °C |
| 5 K | -268.15 °C |
| 6 K | -267.15 °C |
| 7 K | -266.15 °C |
| 8 K | -265.15 °C |
| 9 K | -264.15 °C |
| 10 K | -263.15 °C |
| 11 K | -262.15 °C |
| 12 K | -261.15 °C |
| 13 K | -260.15 °C |
| 14 K | -259.15 °C |
| 15 K | -258.15 °C |
| K | °C |
|---|---|
| 16 K | -257.15 °C |
| 17 K | -256.15 °C |
| 18 K | -255.15 °C |
| 19 K | -254.15 °C |
| 20 K | -253.15 °C |
| 25 K | -248.15 °C |
| 30 K | -243.15 °C |
| 40 K | -233.15 °C |
| 50 K | -223.15 °C |
| 75 K | -198.15 °C |
| 100 K | -173.15 °C |
| 250 K | -23.15 °C |
| 500 K | 226.85 °C |
| 1 000 K | 726.85 °C |
Liquid nitrogen boils at 77 K, which is −196.15 °C.
Deep space background radiation is 2.725 K, or −270.4 °C.
About 5,772 K, or 5,498.85 °C.
°C = K − 273.15, not 273.15 − K. 77 K is −196.15 °C, not +196.15.
Near absolute zero, a 0.15 error is a big fraction of the value. Keep the exact constant.
Some US engineering data uses the Rankine scale (absolute Fahrenheit). Rankine is not kelvin; 1 K = 1.8 °R.
The SI base unit of thermodynamic temperature, with 0 K at absolute zero.
Origin. Named after Lord Kelvin, who proposed an absolute scale in 1848.
Used today. Scientific research, superconductors, astronomy and lighting colour.
A degree Celsius is the same size as one kelvin. The Celsius scale is defined from the Kelvin scale as °C = K − 273.15, so water freezes close to 0 °C and boils close to 100 °C at sea-level pressure.
Origin. From Anders Celsius's 1742 centigrade scale, renamed in 1948.
Used today. Weather, cooking and most everyday temperatures.
26.85 °C, a warm room.
−273.15 °C, absolute zero.
Water's triple point was historically fixed at 273.16 K and 0.01 °C, so 0 °C sits at 273.15 K.
No. Write 300 K, not 300 °K.