Celsius to Kelvin Converter
Enter a temperature in degrees Celsius and instantly convert it to Kelvin.
How to convert Celsius to Kelvin
Converting Celsius to Kelvin is one of the most common temperature conversions in science, engineering, and education. The relationship between both scales is simple: Kelvin uses the same interval size as Celsius, but its zero point is absolute zero instead of the freezing point of water.
To convert Celsius to Kelvin, add 273.15 to the Celsius value:
Kelvin = Celsius + 273.15
Why Kelvin matters
Kelvin is the SI base unit for thermodynamic temperature. Unlike Celsius and Fahrenheit, Kelvin does not use degrees in its symbol. You write it as K, not °K. Scientists prefer Kelvin because it starts at absolute zero, the theoretical point where molecular motion is minimal.
Common use cases for Kelvin
- Physics equations involving gas laws and thermodynamics
- Chemistry calculations and laboratory measurements
- Astronomy and cosmology temperature values
- Engineering systems that depend on absolute temperature
Step-by-step conversion examples
Example 1: Room temperature
If a room is 25°C:
- Add 273.15
- 25 + 273.15 = 298.15 K
Example 2: Freezing point of water
Water freezes at 0°C:
- 0 + 273.15 = 273.15 K
Example 3: Boiling point of water
Water boils at 100°C (at standard atmospheric pressure):
- 100 + 273.15 = 373.15 K
Quick Celsius to Kelvin chart
| Celsius (°C) | Kelvin (K) |
|---|---|
| -273.15 | 0.00 |
| -40 | 233.15 |
| 0 | 273.15 |
| 20 | 293.15 |
| 25 | 298.15 |
| 37 | 310.15 |
| 100 | 373.15 |
Common mistakes to avoid
- Forgetting the .15 in 273.15 and using 273 only when precision matters
- Writing Kelvin with a degree symbol (it should be K, not °K)
- Using values below -273.15°C for physical systems (below absolute zero is not physically valid)
- Rounding too early in multi-step calculations
Frequently asked questions
Is Kelvin the same size as Celsius?
Yes. A change of 1°C is exactly the same temperature interval as a change of 1 K.
Can Kelvin be negative?
In classical thermodynamics for standard physical systems, Kelvin values are not negative. The lowest point is 0 K, which corresponds to -273.15°C.
Do I always add 273.15?
Yes, for Celsius to Kelvin conversion. For Kelvin to Celsius, subtract 273.15.
Final takeaway
The Celsius to Kelvin conversion is straightforward: add 273.15. Use the calculator above to get accurate results in seconds, whether you are studying for exams, working in a lab, or validating engineering data.