Celsius to Kelvin
Convert Celsius to Kelvin instantly for scientific calculations.
How to Use
Enter your Celsius
Type the temperature in Celsius. Negatives and decimals are accepted down to -273.15.
Get the Kelvin instantly
The calculator adds exactly 273.15 to give you the thermodynamic temperature.
Use in your equations
Click the copy button to grab the Kelvin value for your Ideal Gas Law or chemistry equations.
Why Convert Celsius to Kelvin?
In everyday life, Celsius works perfectly fine for talking about the weather or boiling water. But in science—specifically physics and chemistry—Celsius falls apart because it allows for negative numbers. If you're calculating gas volumes or thermodynamic energy, a negative temperature would completely break the math! That's why scientists use Kelvin: it starts at "Absolute Zero" (the coldest theoretically possible temperature where all atomic motion stops) and only goes up from there.
The Core Rule
Kelvin = Celsius + 273.15
Because the "size" of one degree Celsius is exactly the same as one unit of Kelvin, there is no complicated multiplication involved. You simply shift the starting point by adding 273.15.
Scientific Temperature Benchmarks
- Absolute Zero = -273.15°C (0 K)
- Water Freezes = 0°C (273.15 K)
- Standard Room Temperature = 20°C (293.15 K)
- Water Boils = 100°C (373.15 K)
Real-World Examples & Use Cases
Solving the Ideal Gas Law (PV=nRT)
If you're a chemistry or physics student, you've probably lost points on a test for forgetting to convert to Kelvin. When using the Ideal Gas Law (PV=nRT), plugging in a room temperature of 25°C will completely ruin your calculation. You absolutely must convert it to 298.15 K first for the equation to work.
Setting Camera White Balance
Photographers and videographers don't use Kelvin for heat; they use it for color temperature! Daylight is usually rated around 5600K, while warm indoor tungsten bulbs are around 3200K. If you're reading a lighting spec sheet that lists operating temperatures in Celsius, you'll need this conversion to understand how the light will actually look on camera.
Understanding Astronomy and Space
When reading about space, temperatures are almost exclusively given in Kelvin. The surface of the sun is about 5,778 K. The background radiation of the universe is about 2.7 K. Converting these massive (or tiny) Kelvin numbers back to Celsius helps ground them in temperatures we actually understand.
How It Works
Unlike Fahrenheit to Celsius, the Kelvin conversion requires zero multiplication or division. A change of 1 degree Celsius is exactly the same physical amount of heat as a change of 1 Kelvin. The only difference is where the scales begin. Celsius starts at the freezing point of water. Kelvin starts at Absolute Zero (which is -273.15°C). Therefore: Kelvin = Celsius + 273.15. *Note: Notice there is no "degree" symbol for Kelvin. It is officially just "Kelvin" (K), not "degrees Kelvin" (°K).*
Frequently Asked Questions
Can Kelvin be negative?▼
Why do we add 273.15 instead of just 273?▼
Why is there no degree symbol on Kelvin?▼
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