Celsius to Kelvin Converter (°C to K)

How to convert Celsius to Kelvin

K = °C + 273.15

Kelvin is the SI base unit of temperature, built so that 0 K sits at absolute zero - the point at which molecular motion reaches its minimum. Because a kelvin has exactly the same size as a Celsius degree, converting is pure addition: add 273.15.

Note that Kelvin takes no degree symbol: water boils at 373.15 K, not °K.

Worked examples

Convert 25°C: 25 + 273.15 = 298.15 K
Convert 0°C: 0 + 273.15 = 273.15 K (water freezes)
Convert -273.15°C: -273.15 + 273.15 = 0 K (absolute zero)

Celsius to Kelvin conversion table (°C to K)

Celsius (°C)	Kelvin (K)
-40°C	233.15K
-30°C	243.15K
-20°C	253.15K
-10°C	263.15K
0°C	273.15K
10°C	283.15K
20°C	293.15K
30°C	303.15K
40°C	313.15K
50°C	323.15K
60°C	333.15K
70°C	343.15K
80°C	353.15K
90°C	363.15K
100°C	373.15K

Reference temperatures in °C and K

Reference point	°C	K
Absolute zero	-273.15°C	0K
Arctic winter day	-30°C	243.15K
Home freezer	-18°C	255.15K
Water freezes / ice melts	0°C	273.15K
Refrigerator	3°C	276.15K
Cool spring day	10°C	283.15K
Comfortable room	21°C	294.15K
Summer afternoon	30°C	303.15K
Normal body temperature	37°C	310.15K
Hot bath	40°C	313.15K
Death Valley record heat	56.7°C	329.85K
Water boils (sea level)	100°C	373.15K
Moderate oven	180°C	453.15K

Frequently asked questions

Why does the Kelvin scale exist?

Physics equations (gas laws, thermodynamics, radiation) need a scale proportional to actual thermal energy. That requires zero to mean zero energy - absolute zero - which Celsius and Fahrenheit do not provide.

Is 300 K hot or cold?

300 K is 26.85°C (about 80°F) - A warm room or a pleasant summer day.

Why 273.15 exactly?

Absolute zero measures -273.15°C, so shifting Celsius up by that amount places zero at absolute zero while keeping the degree size identical.