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

Full °C to K table: -273.15°C to 1000°C (149 values)

Celsius (°C)	Kelvin (K)
-273.15°C	0K
-250°C	23.15K
-200°C	73.15K
-150°C	123.15K
-100°C	173.15K
-80°C	193.15K
-60°C	213.15K
-50°C	223.15K
-45°C	228.15K
-40°C	233.15K
-39°C	234.15K
-38°C	235.15K
-37°C	236.15K
-36°C	237.15K
-35°C	238.15K
-34°C	239.15K
-33°C	240.15K
-32°C	241.15K
-31°C	242.15K
-30°C	243.15K
-29°C	244.15K
-28°C	245.15K
-27°C	246.15K
-26°C	247.15K
-25°C	248.15K
-24°C	249.15K
-23°C	250.15K
-22°C	251.15K
-21°C	252.15K
-20°C	253.15K
-19°C	254.15K
-18°C	255.15K
-17°C	256.15K
-16°C	257.15K
-15°C	258.15K
-14°C	259.15K
-13°C	260.15K
-12°C	261.15K
-11°C	262.15K
-10°C	263.15K
-9°C	264.15K
-8°C	265.15K
-7°C	266.15K
-6°C	267.15K
-5°C	268.15K
-4°C	269.15K
-3°C	270.15K
-2°C	271.15K
-1°C	272.15K
0°C	273.15K
1°C	274.15K
2°C	275.15K
3°C	276.15K
4°C	277.15K
5°C	278.15K
6°C	279.15K
7°C	280.15K
8°C	281.15K
9°C	282.15K
10°C	283.15K
11°C	284.15K
12°C	285.15K
13°C	286.15K
14°C	287.15K
15°C	288.15K
16°C	289.15K
17°C	290.15K
18°C	291.15K
19°C	292.15K
20°C	293.15K
21°C	294.15K
22°C	295.15K
23°C	296.15K
24°C	297.15K
25°C	298.15K
26°C	299.15K
27°C	300.15K
28°C	301.15K
29°C	302.15K
30°C	303.15K
31°C	304.15K
32°C	305.15K
33°C	306.15K
34°C	307.15K
35°C	308.15K
36°C	309.15K
36.5°C	309.65K
37°C	310.15K
37.5°C	310.65K
38°C	311.15K
38.5°C	311.65K
39°C	312.15K
39.5°C	312.65K
40°C	313.15K
40.5°C	313.65K
41°C	314.15K
42°C	315.15K
43°C	316.15K
44°C	317.15K
45°C	318.15K
46°C	319.15K
47°C	320.15K
48°C	321.15K
49°C	322.15K
50°C	323.15K
55°C	328.15K
60°C	333.15K
65°C	338.15K
70°C	343.15K
75°C	348.15K
80°C	353.15K
85°C	358.15K
90°C	363.15K
95°C	368.15K
100°C	373.15K
110°C	383.15K
120°C	393.15K
130°C	403.15K
140°C	413.15K
150°C	423.15K
160°C	433.15K
170°C	443.15K
180°C	453.15K
190°C	463.15K
200°C	473.15K
210°C	483.15K
220°C	493.15K
230°C	503.15K
240°C	513.15K
250°C	523.15K
260°C	533.15K
270°C	543.15K
280°C	553.15K
290°C	563.15K
300°C	573.15K
350°C	623.15K
400°C	673.15K
450°C	723.15K
500°C	773.15K
550°C	823.15K
600°C	873.15K
650°C	923.15K
700°C	973.15K
750°C	1023.15K
800°C	1073.15K
850°C	1123.15K
900°C	1173.15K
950°C	1223.15K
1000°C	1273.15K

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.