Formula
Kelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.
Celsius to Kelvin Calculator
Convert degrees Celsius to kelvin with the exact 273.15 offset, absolute-zero guardrails and a printable classroom, science or lab worksheet record.
Worked example
For 25 °C, kelvin = 25 + 273.15 = 298.15 K. If the thermometer uncertainty is ±0.2 °C, the converted record is 298.15 K ±0.2 K before any reporting-rounding policy is applied.
Professional note
Master’s Tip: use kelvin for thermodynamic temperature and Celsius for everyday weather or lab readings. Temperature differences have the same numerical size in °C and K, but absolute temperatures need the 273.15 offset.
Regional and unit assumptions
Standard or basis: SI temperature-scale conversion using the exact relation T/K = t/°C + 273.15. This is a measurement and worksheet calculator, not a calibration certificate or safety ruling.
Assumptions and limitations
- The Celsius input is treated as thermodynamic temperature, not a temperature difference unless explicitly used that way in a classroom problem.
- The calculator clamps values below −273.15 °C to absolute zero because ordinary thermodynamic temperature cannot go below 0 K.
- The conversion offset is exact: 0 °C equals 273.15 K.
- Measurement uncertainty is optional and is reported with the same numerical size in kelvin because Celsius and kelvin increments are equal.
- For calibrated laboratory, safety, medical, food, industrial or compliance work, use the instrument certificate, required rounding rule and official procedure.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Kelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.
Standard or basis
Standard or basis: SI temperature-scale conversion using the exact relation T/K = t/°C + 273.15. This is a measurement and worksheet calculator, not a calibration certificate or safety ruling.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: use kelvin for thermodynamic temperature and Celsius for everyday weather or lab readings. Temperature differences have the same numerical size in °C and K, but absolute temperatures need the 273.15 offset.
Related calculators
Questions
How do I convert Celsius to kelvin?
Add 273.15 to the Celsius temperature. For example, 25 °C + 273.15 = 298.15 K.
What is 0 °C in kelvin?
0 °C is exactly 273.15 K.
What is absolute zero in Celsius and kelvin?
Absolute zero is 0 K, which is −273.15 °C.
Is one degree Celsius the same size as one kelvin?
Yes. Celsius and kelvin have the same interval size; their zero points are different.
What should I print for a Celsius-to-kelvin worksheet?
Print the Celsius input, kelvin result, exact formula, rounding increment, uncertainty if used, date, page URL and notes area for the thermometer, classroom problem or lab source.
Calculation note
Celsius and kelvin use the same interval size but different zero points. Adding 273.15 moves a Celsius reading onto the absolute temperature scale used in SI science and thermodynamics.
Celsius is familiar; kelvin is absolute
Celsius is convenient for everyday and laboratory readings because it sits close to water-based reference points. Kelvin starts at absolute zero, which makes it the standard absolute-temperature scale for thermodynamic calculations.
The conversion is an offset, not a multiplier
Celsius-to-kelvin conversion adds 273.15. The interval size does not change, so a change of 1 °C is a change of 1 K, but an absolute temperature such as 25 °C must become 298.15 K.
Rounding should not invent precision
A converted temperature should keep the source measurement and uncertainty visible. Printing the formula, rounding increment and notes area helps prevent a neat kelvin answer from overstating the quality of the original reading.