Celsius to Kelvin Converter

The Kelvin scale starts at absolute zero, the lowest temperature possible, and each step is the same size as one degree Celsius. That makes the conversion a simple shift: add 273.15 to the Celsius value. Kelvin is the SI unit of temperature and is written without a degree sign.

1. 1

   Enter a value

   Type a number into the From box. It starts at 1 so you can see the basic ratio straight away. Thousands separators such as 1,250.5 are accepted.

2. 2

   Choose your units

   This page opens with its own units selected. Use either dropdown to pick any other unit in the category, or tap a unit in the all-units list to make it the target.

3. 3

   Read the result

   The answer updates as you type and the matching formula is shown underneath. There is no Convert button to press.

4. 4

   Swap, copy or clear

   Swap reverses the direction, Copy Result copies a line such as 1 km = 0.621371 mi, and Clear empties the input so you can start again.

Input

• Supported
  Whole numbers25
• Supported
  Decimal numbers2.75

  Use a dot as the decimal separator.

• Supported
  Negative numbers-40

  Calculated for every unit. Quantities such as length or weight are normally positive, while temperatures can be negative.

• Supported
  Thousands separators1,250.5

  Commas must group digits in threes. 1,234 is read as one thousand two hundred thirty-four.

• Supported
  Scientific notation1.5e6

  Useful for very large or very small values (1.5e6 = 1,500,000).

• Not supported
  Comma as decimal mark2,5

  Type 2.5 instead.

• Not supported
  Fractions1/2

  Type 0.5 instead.

• Not supported
  Numbers with unit text5 km

  Enter only the number and choose the unit from the dropdown.

Output

Results use US English formatting (1,234.56) and show up to 2 decimal places with trailing zeros removed. Very small results appear in scientific notation, such as 9.0949e-13, instead of rounding to zero.

Units available in this converter

• Celsius (°C)
• Fahrenheit (°F)
• Kelvin (K)

Common values for the units currently selected above, in both directions.

Tips

• Temperature differences are identical on both scales: a 10 °C rise is also a 10 K rise.
• Kelvin cannot go below 0, so any Celsius value below -273.15 is physically impossible.

• Converts a temperature reading, not a temperature difference. A change of 10 °C is a change of 18 °F, using 9/5 without the +32 offset.
• Values below absolute zero (0 K, -273.15 °C, -459.67 °F) are physically impossible. The tool still calculates them but shows a warning.
• Rankine and Réaumur scales are not supported.
• Results show up to 2 decimal places. Values are not rounded during calculation, and a non-zero result that would display as 0 is shown in scientific notation.