°C to K conversion line
The straight line maps any Celsius reading to Kelvin. The red dot is your value; the smaller dots mark freezing, room, body and boiling temperatures.
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Temperature
Celsius to Kelvin Converter
Convert Celsius (°C) to Kelvin (K) instantly, with the exact one-step formula, a full equivalents readout and a conversion chart. The go-to tool for chemistry, physics and gas-law problems.
Result
298.15 K
How to convert Celsius to Kelvin
Celsius and Kelvin use identical degree sizes, so this is the simplest temperature conversion there is: just shift the zero point. Celsius sets 0 at the freezing point of water, while Kelvin sets 0 at absolute zero, exactly 273.15 degrees lower.
K = °C + 273.15
Worked example
A gas-law problem is set at 25°C, standard room temperature. Add 273.15: 25 + 273.15 = 298.15 K, the value you plug into PV = nRT.
Good to know
Since the degree size is the same, a temperature difference is identical in both scales: a 10°C rise is also a 10 K rise. Kelvin is written without a degree symbol.
Celsius to Kelvin reference table
| Celsius | Kelvin | Where you see it |
|---|---|---|
| −273.15°C | 0 K | Absolute zero |
| 0°C | 273.15 K | Water freezes |
| 20°C | 293.15 K | Room temperature |
| 25°C | 298.15 K | Standard lab reference |
| 37°C | 310.15 K | Body temperature |
| 100°C | 373.15 K | Water boils |
Reference temperatures in Celsius and kelvin
The kelvin and the degree Celsius are the same size, so a temperature difference of 10 °C is also 10 K; only the starting point differs. Kelvin starts at absolute zero, the lowest possible temperature, which is why it has no negative values and why scientific formulas such as the gas laws require it.
| Reference point | Celsius → kelvin |
|---|---|
| Absolute zero | -273.15 °C = 0 K |
| Water freezes | 0 °C = 273.15 K |
| Room temperature | 20 °C = 293.15 K |
| Normal body temperature | 37 °C = 310.15 K |
| Water boils (sea level) | 100 °C = 373.15 K |
| Oven, moderate | 180 °C = 453.15 K |
Frequently asked questions
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius value. For example, 25°C + 273.15 = 298.15 K.
What is 0°C in Kelvin?
0°C, the freezing point of water, equals 273.15 K.
Why is the offset 273.15 and not 273?
Absolute zero is exactly −273.15°C, so 273.15 aligns the scales precisely; rounding to 273 adds a 0.15-degree error.
Do Celsius and Kelvin degrees have the same size?
Yes. A change of 1°C equals a change of exactly 1 K, so only the zero point differs.
What is absolute zero in Celsius?
0 K equals −273.15°C, the lowest temperature that can exist.
Do I write °K or K?
Just K. The kelvin is an SI base unit and does not take a degree symbol.
Why add 273.15 to convert Celsius to kelvin?
Absolute zero is −273.15 °C, and the kelvin scale starts at absolute zero, so every Celsius value is 273.15 higher in kelvin.
Do you write degrees with kelvin?
No. It is written as K without a degree sign, for example 300 K.
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