Celsius to Kelvin Converter (°C to K) with Formula

To convert Celsius to Kelvin, add 273.15: K = °C + 273.15. So 100 °C equals 373.15 K and 0 °C equals 273.15 K. Unlike most unit conversions, this is an offset rather than a multiplication, because the two scales share the same degree size but start counting from different zero points.

The formula

The conversion is a simple addition. A change of one degree Celsius is exactly one Kelvin, so you only shift the starting point by 273.15.

K = °C + 273.15
Example: 37 °C + 273.15 = 310.15 K

Kelvin is the SI base unit of temperature and its zero (0 K) is absolute zero, the coldest possible temperature. Because the increments match, no scaling factor is ever needed.

Conversion table

How to convert online

You do not need to do the arithmetic by hand:

1. Type your Celsius value into the first box.
2. Read the Kelvin result instantly in the second box.
3. Type a Kelvin value instead to convert back — it works both ways.

Use the Celsius to Kelvin Converter — free and instant in your browser.

Where this conversion is used

Kelvin is the standard scale in physics, chemistry and engineering, so students and researchers convert Celsius readings to Kelvin for gas laws, thermodynamics, spectroscopy and colour-temperature work. It also appears in weather science, cryogenics and astronomy, where absolute temperatures matter more than everyday °C readings.

FAQ

What is 0 °C in Kelvin?

Zero degrees Celsius equals 273.15 K, the freezing point of water. Because the scales use an offset rather than a ratio, 0 °C is not 0 K.

What is 100 °C in Kelvin?

100 °C, the boiling point of water at sea level, equals 373.15 K (100 + 273.15).

Is the conversion exact?

Yes. The offset 273.15 is defined exactly, so the conversion has no rounding error — the only approximation is any rounding you choose in the final digits.

How do I convert Kelvin back to Celsius?

Subtract 273.15: °C = K − 273.15. Our Kelvin to Celsius converter uses the same exact offset so the numbers always match.

Related converters

• Kelvin to Celsius Converter
• Celsius to Fahrenheit Converter

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