Celsius to Kelvin Conversion

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Formula to Convert Celsius to Kelvin

We can measure temperature with the help of three different scales, which are Celsius, Kelvin, and Fahrenheit scales. The Celsius scale is also called a Centigrade scale sometimes, however, it is outdated. The Celsius scale is defined by an international agreement in regards to two fixed points, the stream point, and the ice point. The temperature of the stream point is defined as 100° celsius while that of the ice point is defined as 0° celsius. 

Kelvin is the fraction \[\frac{1}{273.16}\] of the thermodynamic temperature of water’s triple point. The unit of the thermodynamic temperature scale is known as the Kelvin. Today we will learn how to convert degree celsius into kelvin and the formula to convert celsius to kelvin.

Absolute Temperature

It is known that the universe has a minimum temperature, however, it is not obvious until there is a better physical temperature interpretation. Several experiments measure the pressure against temperature keeping the volume and mass constant. They tend to show the same results. Generally, the pressure-temperature graphs of different gases show different slopes, however, they conclude to the same temperature at zero pressure just like the volume-temperature graphs did at zero volume. The smallest possible pressure is zero, therefore, the temperature intercept in the minimum temperature that is possible. This is referred to as the absolute zero.

The Kelvin scale is dependent on these experiments. However, it is not arbitrary but is designed in a way that the zero point is the absolute zero.

0K = - 273.15°C = -459.67°F

Kelvin, denoted by K, is known as the official metric unit for temperature. You would see here that there is no degree sign used with the Kelvin scale. For example, 2K is known as two Kelvin. 

Given below is the Celsius to Kelvin conversion formula.

T = T\[_{C}\] + 273.15

Similarly, the Kelvin to Celsius conversion formula is,

T\[_{C}\] = T -  273.15

The kelvin temperature scale is designed in a way that one degree Celsius and one Kelvin equal the same.

Celsius to Kelvin Conversion Factor

Let us learn how to convert a degree into kelvin and other conversion formulas.

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1. Degree Celsius to Kelvin

K = C + 273.15

2. Degree Celsius to Degree Fahrenheit

F = (\[\frac{9}{5}\])C + 32

3. Degree Fahrenheit to Degree Celsius

C = (\[\frac{5}{9}\])(F - 32)

4. Degree Fahrenheit to Kelvin

K = (\[\frac{5}{9}\])(F + 459.67)

5. Degree Fahrenheit to Rankin

R = F + 459.67

6. Degree Rankin to Kelvin

K = (\[\frac{5}{9}\])R

Units of SI System

  1. The basic unit of temperature according to the SI system is Kelvin. However, it can turn out to be impractical in several cases.

  2. The Celsius scale of temperature, on the other hand, is often used in the clinical laboratory. Both the Celsius and Kelvin scales are related to one another closely and the conversion formula for Celsius to Kelvin scales is simple since both the units are equal to each other in magnitude.

  3. The only difference between the Celsius and Kelvin scales is the zero point. The zero points on the Celsius scale refers to the freezing point of water. On the other hand, the zero points on the Kelvin scale refers to the theoretical temperature at no heat loss further, which is the absolute zero. However, the magnitude of the degree is the same in both the scales. 

Celsius to Kelvin Formula

Let us learn about how to convert celsius to kelvin formula.

Water freezes at 0 degrees Celsius, which equals 273 Kelvin. Also, 0 Kelvin is equal to -273 degrees Celsius. Hence, to convert degree to Kelvin, add 273 to Celsius degree. And for converting Kelvin to Celsius, simply subtract 273.

K = °C + 273

°C = K - 273

The table below gives a comparative reading of all the three temperature scales having common reference points.

Reference Point

Degrees Fahrenheit


Degrees Celsius

Boiling point of water




Body temperature




Room temperature




Freezing point of water




Absolute zero




Let us take a look at how to change the temperature from Celsius to Kelvin with the help of an example.

Solved Example

The boiling point of ethyl alcohol is 78.5°C and its freezing point is -117°C at 1 atm pressure. Determine these temperatures at the Kelvin scale.


To convert degree Celsius to Kelvin,

K = °C + 273

Hence, the boiling point is

= 78.5 + 273.15 

= 351.7 K

Similarly, the freezing point is

= -117 + 273.15 

= 156K

FAQ (Frequently Asked Questions)

1. Why Do We Use the Kelvin Temperature Scale?

Answer: The Kelvin temperature scale begins at absolute zero. Zero Kelvin denotes zero temperature or kinetic energy. Due to this, there is a change from 100 K to 200 K which represents the doubling of the system’s kinetic energy. Since volume is directly proportional to temperature, the doubling of temperature in the kelvin scale results in the doubling of volume as well. The change in the Celsius or Fahrenheit scale, on the other hand, is not related directly to the kinetic energy or the volume since these scales do not begin at zero.

Scientists make use of the Kelvin scale since it is referred to as an absolute temperature scale which is directly related to the kinetic energy and volume.

2. At Which Temperature are Celsius and Kelvin Equal?

Answer: There is no such temperature at which the Celsius and Kelvin are equal. The Kelvin temperature scale is known to be a variation of the Celsius scale. The degree size is the same and the only difference is that 0 Celsius is the freezing point of water whereas 0 Kelvin is the absolute zero. The Kelvin scale exists since several equations have a zero point at the absolute zero, which is -273°C. Hence for simplifying the equations the temperature variable is defined as the temperature in Kelvin, wherein, K = °C + 273. One such example of this type of equation is the ideal gas equation.