Celsius to Kelvin

What is Celsius?

Celsius is the everyday temperature scale used by most of the world, with water freezing at 0°C and boiling at 100°C. It is part of the International System of Units (SI) and is the standard for non-scientific temperature measurement in nearly every country except the United States.

The Celsius scale shares the same increment size as Kelvin, making conversion between the two a simple addition or subtraction. This is why Celsius is often used alongside Kelvin in scientific contexts.

What is Kelvin?

Kelvin is the SI base unit of temperature, named after British physicist William Thomson, 1st Baron Kelvin. Unlike Celsius and Fahrenheit, Kelvin is an absolute temperature scale — its zero point (0 K) is absolute zero, the theoretical temperature at which all thermal motion ceases. There are no negative Kelvin temperatures in classical thermodynamics.

One Kelvin has the same magnitude as one degree Celsius, so the conversion is simply K = °C + 273.15. Water freezes at 273.15 K and boils at 373.15 K. Kelvin is used extensively in physics, chemistry, and engineering, especially in thermodynamics and low-temperature research.

When to convert Celsius to Kelvin

Conversion between Celsius and Kelvin is needed in many scientific fields:

• Thermodynamics. Gas laws and thermodynamic equations require absolute temperatures in Kelvin.
• Chemistry. Reaction rates and equilibrium constants use Kelvin in their formulas.
• Physics. Black-body radiation and the Stefan-Boltzmann law require Kelvin.
• Cryogenics. Low-temperature physics reports results in Kelvin.

How to convert Celsius to Kelvin

This tool converts instantly in your browser.

1. Enter a value. Type a Celsius temperature in the input box.
2. See the result. The Kelvin equivalent appears immediately.
3. Copy if needed. Click "Copy result" to copy the value.

The formula is K = °C + 273.15. For example, 25°C = 25 + 273.15 = 298.15 K. All math is local and private.

Common Celsius to Kelvin values

Frequently used temperature conversions:

Celsius	Kelvin	Description
-273.15°C	0 K	Absolute zero
0°C	273.15 K	Freezing point of water
25°C	298.15 K	Standard room temperature
37°C	310.15 K	Body temperature
100°C	373.15 K	Boiling point of water