Convert Celsius to Kelvin
Convert Celsius to Kelvin instantly. Add 273.15 to move from the metric scale to the absolute scientific temperature scale.
How to Convert Celsius to Kelvin
To convert Celsius to Kelvin, add 273.15 to the Celsius value.
Conversion Formula:
value + 273.15Understanding the Conversion
Celsius to Kelvin is the bridge between everyday temperatures and the absolute scale used in science. Kelvin shares the same degree size as Celsius but starts at absolute zero, so you only need to shift by 273.15. This makes Kelvin ideal for thermodynamics, gas laws, cryogenics, and any calculation requiring true absolute temperature values.
The formula is simple: K = °C + 273.15. Freezing water at 0°C becomes 273.15 K, boiling water at 100°C becomes 373.15 K, and room temperature around 22°C becomes 295.15 K. Because the step size is identical, differences and gradients stay the same: a 10-degree change in Celsius equals a 10-kelvin change.
Use this conversion in chemistry and physics labs, HVAC and refrigeration calculations, materials testing, and engineering models where absolute temperature is required. Kelvin eliminates negative values, making equations like the ideal gas law or Carnot efficiency easier to apply without sign confusion. The converter preserves decimal precision so your calculations remain accurate for research or industrial controls.
Keep in mind that temperatures in Kelvin are always positive because absolute zero is unreachable. Adding 273.15 is all you need to reposition a Celsius reading onto the absolute scale.
Conversion Examples
Example: Convert 25°C to Kelvin
- Step 1: Add 273.15.
- Step 2: 25 + 273.15 = 298.15.
- Step 3: Result is 298.15 K.
25°C = 298.15 K
Typical room temperature in Kelvin for scientific calculations.
Example: Convert 100°C (boiling water) to Kelvin
- Step 1: 100 + 273.15 = 373.15.
- Step 2: No further steps needed.
- Step 3: Result is 373.15 K.
100°C = 373.15 K
Boiling point of water at sea level in Kelvin.
Example: Convert -20°C to Kelvin
- Step 1: -20 + 273.15 = 253.15.
- Step 2: Result stays positive because Kelvin is absolute.
- Step 3: Final value is 253.15 K.
-20°C = 253.15 K
Even sub-freezing Celsius temperatures remain positive on the Kelvin scale.
Conversion Formula
Celsius and Kelvin use the same step size. Kelvin starts at absolute zero, which is −273.15°C, so adding 273.15 shifts any Celsius reading onto the absolute scale.
Conversion Chart
| Celsius | Kelvin |
|---|---|
| -50 | 223.15 |
| -20 | 253.15 |
| 0 | 273.15 |
| 10 | 283.15 |
| 20 | 293.15 |
| 25 | 298.15 |
| 30 | 303.15 |
| 50 | 323.15 |
| 75 | 348.15 |
| 100 | 373.15 |
Quick Conversion Tip
Just add 273.15. Differences are identical: a 15°C rise equals a 15 K rise.
Unit Definitions
Celsius (°C)
Metric temperature scale with 0° at water freezing and 100° at boiling under standard pressure.
Shares degree size with Kelvin. Add 273.15 to reach Kelvin and subtract 273.15 from Kelvin to return to Celsius.
Kelvin (K)
Absolute temperature scale used in science and engineering, starting at absolute zero.
Same increment as Celsius but shifted by +273.15. Kelvin to Celsius subtracts 273.15; Kelvin to Fahrenheit uses (K − 273.15) × 9/5 + 32.
Common Use Cases
- Physics and chemistry experiments needing absolute temperature.
- Engineering thermodynamics, heat transfer, and energy calculations.
- HVAC and refrigeration performance metrics that use Kelvin.
- Material science and cryogenics where absolute zero reference is required.
- Academic problem solving for gas laws and efficiency equations.
- Calibration of sensors that report in Celsius but models use Kelvin.
Frequently Asked Questions
Why add 273.15 and not 273?
273.15 is the precise offset between Celsius and Kelvin based on absolute zero and the triple point of water.
Can Kelvin values be negative?
No. Kelvin is an absolute scale starting at 0 K. Negative Kelvin would imply temperatures below absolute zero, which are not physically attainable in classical thermodynamics.
Do temperature differences stay the same?
Yes. A change of 1°C equals a change of 1 K because the step size is identical.