Celsius to Kelvin Converter

Convert Celsius (°C) to Kelvin (K) instantly, with the exact one-step formula, a full equivalents readout and a conversion chart. The go-to tool for chemistry, physics and gas-law problems.

Result

298.15 K

°C to K conversion line

The straight line maps any Celsius reading to Kelvin. The red dot is your value; the smaller dots mark freezing, room, body and boiling temperatures.

How to convert Celsius to Kelvin

Celsius and Kelvin use identical degree sizes, so this is the simplest temperature conversion there is: just shift the zero point. Celsius sets 0 at the freezing point of water, while Kelvin sets 0 at absolute zero, exactly 273.15 degrees lower.

K = °C + 273.15

Worked example

A gas-law problem is set at 25°C, standard room temperature. Add 273.15: 25 + 273.15 = 298.15 K, the value you plug into PV = nRT.

Good to know

Since the degree size is the same, a temperature difference is identical in both scales: a 10°C rise is also a 10 K rise. Kelvin is written without a degree symbol.

Celsius to Kelvin reference table

Celsius	Kelvin	Where you see it
−273.15°C	0 K	Absolute zero
0°C	273.15 K	Water freezes
20°C	293.15 K	Room temperature
25°C	298.15 K	Standard lab reference
37°C	310.15 K	Body temperature
100°C	373.15 K	Water boils

Frequently asked questions

How do I convert Celsius to Kelvin?

Add 273.15 to the Celsius value. For example, 25°C + 273.15 = 298.15 K.

What is 0°C in Kelvin?

0°C, the freezing point of water, equals 273.15 K.

Why is the offset 273.15 and not 273?

Absolute zero is exactly −273.15°C, so 273.15 aligns the scales precisely; rounding to 273 adds a 0.15-degree error.

Do Celsius and Kelvin degrees have the same size?

Yes. A change of 1°C equals a change of exactly 1 K, so only the zero point differs.