1 celsius = 274.15 K
1 °C = 274.15 K · type math like (12*4)+6.5
Celsius to kelvin is a science and engineering conversion. Gas law calculations, thermodynamics homework, colour temperature for lighting, and spacecraft and cryogenics data all require absolute temperature in kelvin.
Lighting and photography borrow the kelvin for colour temperature. A warm incandescent bulb is about 2,700 K, daylight is around 5,500–6,500 K, and an overcast sky can exceed 7,000 K. These numbers are not converted from Celsius in everyday use, but they are true kelvin values on the same scale.
Chemistry students meet this conversion in every gas law problem. Standard temperature and pressure (STP) uses 0 °C, which is 273.15 K, while many textbooks and IUPAC also refer to standard ambient conditions of 25 °C, or 298.15 K. Forgetting to convert is the most common mistake in these problems.
Because Celsius and kelvin steps are the same size, temperature differences are identical in both. A reaction that heats from 20 °C to 80 °C rises 60 K. Only absolute values need the 273.15 offset.
Industrial processes such as steelmaking also quote kelvin in research papers. Iron melts at 1,538 °C, which is 1,811.15 K.
Cryogenic storage uses liquid nitrogen at −196 °C, which is 77.15 K.
Room temperature of 20 °C is 293.15 K.
To check, a kelvin figure is always 273.15 higher than the Celsius figure and can never be negative. If you convert a freezer at −18 °C and get a negative kelvin value, you subtracted instead of added; the correct answer is 255.15 K. In laboratory reports, keep two decimal places so the 0.15 offset is not lost when values are later converted back or used in further calculations.
K = °C + 273.15
Reverse: 1 K = -272.15 °C.
Convert 25 °C to kelvin.
Answer: 25 °C = 298.15 K.
| °C | K |
|---|---|
| -40 °C | 233.15 K |
| -30 °C | 243.15 K |
| -20 °C | 253.15 K |
| -10 °C | 263.15 K |
| 0 °C | 273.15 K |
| 1 °C | 274.15 K |
| 2 °C | 275.15 K |
| 3 °C | 276.15 K |
| 4 °C | 277.15 K |
| 5 °C | 278.15 K |
| 6 °C | 279.15 K |
| 7 °C | 280.15 K |
| 8 °C | 281.15 K |
| 9 °C | 282.15 K |
| 10 °C | 283.15 K |
| 11 °C | 284.15 K |
| 12 °C | 285.15 K |
| °C | K |
|---|---|
| 13 °C | 286.15 K |
| 14 °C | 287.15 K |
| 15 °C | 288.15 K |
| 16 °C | 289.15 K |
| 17 °C | 290.15 K |
| 18 °C | 291.15 K |
| 19 °C | 292.15 K |
| 20 °C | 293.15 K |
| 25 °C | 298.15 K |
| 30 °C | 303.15 K |
| 40 °C | 313.15 K |
| 50 °C | 323.15 K |
| 75 °C | 348.15 K |
| 100 °C | 373.15 K |
| 250 °C | 523.15 K |
| 500 °C | 773.15 K |
| 1 000 °C | 1 273.15 K |
25 °C is 298.15 K, the standard reference temperature in chemistry tables.
100 °C is 373.15 K.
−273.15 °C is 0 K, the lowest possible temperature.
For most purposes 273 is fine, but in precise work the 0.15 matters, for example in vapour pressure tables.
The unit is simply kelvin (K), not °K.
PV = nRT needs kelvin. Doubling from 10 °C to 20 °C does not double pressure; going from 283 K to 293 K only raises it 3.5%.
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. Celsius's 1742 scale was later linked to the kelvin, so that a 1 °C step equals a 1 K step exactly.
Used today. Everyday and laboratory temperature reporting in most countries.
The kelvin is the SI base unit of temperature. Since 2019 it is defined by fixing the Boltzmann constant at 1.380649 × 10⁻²³ J/K. 0 K is absolute zero.
Origin. Named after William Thomson, Lord Kelvin, who described an absolute temperature scale in 1848. The degree sign was dropped in 1967, so it is written 300 K, not 300 °K.
Used today. Physics, chemistry, astronomy, cryogenics and lamp colour temperatures.
No. 0 K is absolute zero, so all kelvin temperatures are zero or positive.
Yes. The step sizes are identical; only the zero point differs.
273.15 K.
It is the colour temperature, the hue a heated black body would glow at 5000 K, which looks like neutral daylight.