Convert Celsius to Kelvin (°C → K)

Celsius is the global temperature standard for weather, science, and daily life outside the United States.

Celsius

Kelvin

274.15

1 °C274.15 KNIST · BIPM accuracy

Celsius to Kelvin Conversion Table

10 common values

Celsius	Kelvin
-40 °C	233.15 K
-20 °C	253.15 K
0 °C	273.15 K
10 °C	283.15 K
20 °C	293.15 K
25 °C	298.15 K
30 °C	303.15 K
37 °C	310.15 K
100 °C	373.15 K
200 °C	473.15 K

How to Convert Celsius to Kelvin Manually

Step by Step

Temperature scales differ in both zero-point and degree size, so conversion uses a formula — not simple multiplication. Follow these steps to convert degrees Celsius to kelvins by hand.

1
Take your value in degrees Celsius
Start with the number of degrees Celsius (°C) you want to convert.
2
Apply the formula
Use the formula: K = °C + 273.15
3
Read the result in kelvins
The result is your value in kelvins (K).

Practical Examples

1 °C

equals

274.15 K

5 °C

equals

278.15 K

10 °C

equals

283.15 K

25 °C

equals

298.15 K

100 °C

equals

373.15 K

Formula

Temperature conversion uses an offset formula, not simple multiplication.

ForwardK = °C + 273.15

Reverse°C = K − 273.15

Tips

Use these in everyday conversions

0 °C = freezing; 100 °C = boiling. Easy anchor points.
Mental F conversion: double the °C and add 30 (rough). 20 °C → 70 °F (actual 68).
Medical thermometers show 0.1 °C resolution — a rise from 37.0 to 37.5 matters.

Common Mistakes

Avoid these

Using "degrees centigrade" — the scale was renamed Celsius in 1948.
Assuming a linear relationship between °C and °F without the +32 offset.
Interpreting UK winter forecasts in °F by habit — UK uses °C.

About Celsius and Kelvin

What is the Celsius?

Celsius is the global temperature scale used for weather forecasts, science, medicine, and daily life in all countries except the United States. Originally proposed by Swedish astronomer Anders Celsius in 1742 (with 0° as boiling and 100° as freezing — the inverse of today's scale), the modern version was reversed shortly after his death. Since 2019, Celsius has been redefined via the Kelvin scale: 0°C is exactly 273.15 K, and 1°C equals 1 K in size. Water freezes at 0°C, boils at 100°C at sea level, and human body temperature is around 37°C. Comfortable room temperature is about 20–22°C, and a hot summer day is 30–35°C. Celsius relates to Fahrenheit by the formula °F = °C × 9/5 + 32, and to Kelvin by adding 273.15. The scale's decimal-friendly division of water's phase transitions made it the natural metric choice.

Daily weather forecasts worldwide (except US)
Cooking temperatures in Europe, Asia, Latin America
Body temperature on medical thermometers

Real-world examples

Room temperature is about 20 °C. Normal body temperature is 37 °C. Typical fridge setting is 4 °C. European winter can reach −20 °C; desert summer 45+ °C.

What is the Kelvin?

The Kelvin is the SI base unit of thermodynamic temperature, named after British physicist William Thomson, 1st Baron Kelvin (1824–1907), who proposed an absolute temperature scale in 1848. Kelvin starts at absolute zero — the theoretical lowest temperature where all classical molecular motion stops — at exactly 0 K. The Kelvin uses the same degree size as Celsius: 0°C = 273.15 K, water boils at 373.15 K. Note that Kelvin temperatures are not preceded by a degree sign (300 K, not 300°K). The Kelvin is essential in scientific work — gas laws, blackbody radiation, cryogenics, and astrophysics all use absolute temperature. Since 2019, the Kelvin has been defined by fixing the numerical value of the Boltzmann constant (k = 1.380649 × 10⁻²³ J/K). The Kelvin relates to Celsius by addition (K = °C + 273.15) and is universally used in physics and chemistry.