Convert Celsius to Kelvin – Temperature Converter
This tool converts a temperature value in degrees Celsius (°C) to kelvin (K). The conversion is a fixed linear offset and is exact by definition: one kelvin has the same magnitude as one degree Celsius, only the zero point differs.
Use the converter for scientific, engineering, educational, and workplace calculations. For measurements used in compliance or calibration activities, follow laboratory traceability and calibration best practices referenced below.
Interactive Converter
Convert between celsius and kelvin with precision rounding.
Quick reference table
| Celsius | Kelvin |
|---|---|
| 1 °C | 274.15 K |
| 5 °C | 278.15 K |
| 10 °C | 283.15 K |
| 25 °C | 298.15 K |
| 50 °C | 323.15 K |
| 100 °C | 373.15 K |
Methodology
The conversion is a dimension-preserving linear offset: kelvin equals the Celsius temperature plus 273.15. This is an exact relationship used in engineering and science and consistent with international measurement practice.
When using measured temperatures rather than calculated values, consider sensor uncertainty, instrument calibration, and environmental effects. Calibration and uncertainty statements should follow recognized standards such as ISO/IEC 17025 for calibration laboratories and the international temperature scales maintained by national metrology institutes.
This converter provides mathematical conversion only. For regulatory, safety, or compliance use, pair the numeric conversion with calibrated instruments and documented traceability to national standards (for example, NIST or the national metrology institute in your jurisdiction).
Worked examples
25 °C → 25 + 273.15 = 298.15 K
-273.15 °C → -273.15 + 273.15 = 0 K (absolute zero)
100 °C → 100 + 273.15 = 373.15 K
Key takeaways
Conversion is exact: add 273.15 to °C to obtain K.
Kelvin uses no degree symbol; the unit symbol is K.
For measured temperatures, account for instrument uncertainty and calibration traceability.
Expert Q&A
Is the conversion between Celsius and kelvin exact?
Yes. The size of one kelvin equals one degree Celsius and the offset is exactly 273.15, so K = °C + 273.15 is exact as a mathematical relation between the two scales.
Can Kelvin be negative?
No. By definition of the thermodynamic temperature scale, 0 K is absolute zero (equivalent to -273.15 °C). Values below 0 K are not physically meaningful on the kelvin scale used here.
Should I round results and how many decimals are appropriate?
Rounding depends on the measurement or calculation context. For display, two decimal places (e.g., 298.15 K) is common. For scientific work, match rounding to the uncertainty of your measured or reported temperature and follow your discipline's significant-figure conventions.
Does this converter account for sensor error or calibration uncertainty?
No. This converter performs the mathematical unit conversion only. When converting measured temperatures for compliance, record instrument uncertainty, calibration date, and traceability to a recognized standard such as ISO/IEC 17025 or national metrology institute references.
Why is the offset 273.15?
The offset historically ties to the Celsius scale definition based on the triple point of water and the relationship established between the Celsius and kelvin scales. Modern definitions preserve the fixed offset so that the conversion remains exact.
What symbol should I use for kelvin?
Use the uppercase letter K without a degree symbol. For Celsius use °C.
Sources & citations
- NIST — Temperature and Thermometry resources — https://www.nist.gov/pml/weights-and-measures/temperature
- BIPM — Kelvin (measurement unit information) — https://www.bipm.org/en/measurement-units/kelvin
- ISO/IEC 17025 — General requirements for the competence of testing and calibration laboratories — https://www.iso.org/standard/66912.html
- ISO 80000-5 — Quantities and units: Thermodynamics (context for temperature units) — https://www.iso.org/standard/30668.html
- OSHA — Heat exposure and workplace guidance — https://www.osha.gov/heat-exposure