Celsius to Kelvin Converter

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Enter a Celsius temperature to get its Kelvin value, or choose temperature change for a rise or drop in kelvins.

Advanced options
Celsius value converted to kelvinsK
How this conversion was calculated
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How to use our Celsius to Kelvin Converter

  1. Choose Temperature reading for one measured temperature, or Temperature change for a rise, drop, range, or delta T.
  2. Enter the signed Celsius number from the thermometer, lab note, or science problem.
  3. Choose result decimal places in Advanced options if your assignment specifies rounding, then click Calculate.
  4. Check the calculation note. A temperature reading adds 273.15, while a temperature change keeps the same numerical value.
Example inputs for Celsius to Kelvin Converter
Example inputs for Celsius to Kelvin Converter

Definitions

Celsius temperature (deg C): A temperature reading on the Celsius scale, such as 25 deg C.

Kelvin (K): The SI base unit for thermodynamic temperature. Kelvin values use K without a degree symbol.

Absolute zero: The lowest thermodynamic temperature, equal to 0 K and -273.15 deg C.

Temperature change: A temperature rise, drop, or interval. A change of 1 deg C has the same size as a change of 1 K.

Common mistakes and quick fixes

Mistake: Treating a temperature rise or drop as a temperature reading.
Fix: Choose Temperature change. A rise of 10 deg C is a rise of 10 K, not 283.15 K.

Mistake: Leaving out 273.15 for an absolute Celsius temperature.
Fix: Choose Temperature reading. The converter adds 273.15 to the Celsius reading.

Mistake: Entering a reading below -273.15 deg C.
Fix: Enter -273.15 deg C or higher. A lower absolute temperature is not physically valid.

Mistake: Writing a degree symbol before K.
Fix: Write kelvin values as K, such as 298.15 K, not deg K.

Mistake: Using a comma as a decimal separator, such as 1,5.
Fix: Use a decimal point, such as 1.5. A comma is only for a thousands separator.

Limitations & Key Assumptions / Boundary Conditions

  • This converter handles Celsius readings and Celsius temperature changes only; it does not convert Fahrenheit or other scales.
  • Temperature reading mode accepts -273.15 deg C or higher because lower readings are below absolute zero.
  • Temperature change mode can return a negative, zero, or positive value. A negative value means a temperature drop, not a negative absolute temperature.
  • Result decimal places change only the displayed rounding, not the conversion calculation.
  • Do not add 273.15 to a value that is already in K, including a color temperature labeled in K.

Methodology

Calculation rules

For an absolute temperature reading, the converter adds the exact offset of 273.15. Celsius and kelvin intervals are the same size, so a temperature change keeps the same number.

K = deg C + 273.15

Use this rule for a temperature reading.

delta K = delta deg C

Use this rule for a temperature change. Delta means change.

Worked example

A reading of 25 deg C converts to 298.15 K because 25 + 273.15 = 298.15. A drop of -12.5 deg C converts to -12.5 K because Celsius and kelvin changes have equal numerical size.

Rounding

The converter calculates before rounding the displayed value. Automatic formatting uses ordinary decimals for typical values and scientific notation for very small or very large nonzero values.