Celsius to Kelvin Converter
Converts celsius to kelvin (°C to K) and back. The conversion factor is shown below every result.
How to Convert Celsius to Kelvin
What Is a Celsius?
Degree Celsius (°C) is a temperature scale where 0°C is the freezing point of water at standard atmospheric pressure.
What Is a Kelvin?
The kelvin (K) is the SI base unit of thermodynamic temperature, with 0 K (absolute zero) equal to −273.15°C.
Common Celsius to Kelvin Reference Points
Real-world reference values for quick sanity checks.
| Item | Celsius (°C) | Kelvin (approx.) |
|---|---|---|
| Absolute zero | -273.15 °C | 0 K |
| Water freezes | 0 °C | 273.15 K |
| Room temperature | 21 °C | 294.15 K |
| Water boils | 100 °C | 373.15 K |
| Reference values are illustrative approximations for common items, not measured specifications. | ||
Celsius to Kelvin Conversion Table
| Celsius (°C) | Kelvin (K) |
|---|---|
| -273.15 °C | 0 K |
| -40 °C | 233.15 K |
| 0 °C | 273.15 K |
| 20 °C | 293.15 K |
| 25 °C | 298.15 K |
| 37 °C | 310.15 K |
| 100 °C | 373.15 K |
| Source: NIST SP 811, Appendix B; BIPM SI Brochure, 9th ed. (K = °C + 273.15) | |
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.
Why 273.15 specifically?
Absolute zero, the coldest physically possible temperature, sits at −273.15°C. The Kelvin scale starts counting from absolute zero, so adding 273.15 to a Celsius value shifts it onto the Kelvin scale.
Do Kelvin temperatures use the degree symbol?
No. By SI convention, Kelvin values are written as "K" without a degree symbol (e.g., 298.15 K, not 298.15°K), because the kelvin is treated as an absolute unit rather than a degree offset.
Related Temperature Converters
A good measuring tool marked in both °C and K removes the guesswork at the point of use.