Convert Temperature from Kelvin to Degree Celsius (K to C)

Kelvin to degree Celsius Conversion Formula

To convert from Kelvin (K) to degree Celsius (C), use the following formula:

Example

Let's convert 5 Kelvin (K) to degree Celsius (C).

Using the formula:

Therefore, 5 Kelvin (K) is equal to $-268.15$ degree Celsius (C).

What is a Kelvin (K)?

The kelvin (K) is a unit of measurement for temperature, similar to the Celsius and Fahrenheit scales. What sets it apart?

Most people typically refer to temperature in Fahrenheit or Celsius. Still, scientists favor Kelvin due to its status as an absolute scale. This means it starts at the lowest possible temperature in the universe, making it ideal for accurate scientific research.

It's also one of the seven base units in the International System of Units (SI).

What Is Absolute Zero?

The Kelvin scale begins at 0 K, a point known as absolute zero. This isn't just a random number—it's the theoretical temperature where all atomic motion would completely stop. It's the ultimate cold.

Unlike Celsius, where 0° is the freezing point of water, 0 K is based on a fundamental truth of the universe. This non-arbitrary starting point is why scientists in fields like physics and astronomy rely on it.

Why Is the Kelvin Scale Important?

While you won't use Kelvin to check the daily weather, it's essential in many scientific and technological fields.

• Astronomers use it to measure the frigid temperatures of deep space and the scorching heat of stars.
• Physicists need it for experiments in quantum mechanics and superconductivity.
• Engineers use it when working with materials at extreme temperatures, from rocket engines to medical MRI machines.

How to Convert Between Kelvin and Celsius

The good news is that converting between Kelvin and Celsius is very easy. The size of one unit is identical in both scales, meaning a change of 1 K is the same as a change of 1 °C.

Here are the conversion formulas you need:

• To convert Celsius to Kelvin: Add 273.15 to your Celsius temperature.
  • Formula: K = °C + 273.15
• To convert Kelvin to Celsius: Subtract 273.15 from your Kelvin temperature.
  • Formula: °C = K - 273.15

Examples:

• Water freezes at 0 °C, which is 273.15 K.
• A pleasant room temperature is approximately 20 °C, which corresponds to 293.15 K.
• Water boils at 100 °C, which is 373.15 K.

Who Invented the Kelvin Scale?

The scale is named after its inventor, the brilliant Scottish engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907). In 1848, he introduced an "absolute" thermometric scale beginning at what he called "infinite cold" — the temperature now known as absolute zero. His work established the foundational principles of a measurement system central to modern science.

What is a degree Celsius (°C)?

A degree Celsius (°C) is one of the most common units for measuring temperature around the world. As a key part of the metric system, it's used in everything from daily weather forecasts to scientific research. It offers a straightforward and rational method for gauging the temperature of an object. The plural version is degrees Celsius.

Why Is Celsius Based on Water's Freezing and Boiling Points?

The Celsius scale is cleverly based on the physical properties of water. This relationship to a familiar substance makes it very easy to understand. Let's break it down simply:

• 0 °C is set as the freezing point of water.
• 100 °C is set as the boiling point of water.

This perfect 100-degree interval between freezing and boiling is why it was initially called a "centigrade" scale (from "centi-" meaning 100). This straightforward system is the reason Celsius is the standard for temperature measurement in most countries.

Who Invented the Celsius Scale (And Was It Backwards)?

In 1742, the Swedish astronomer Anders Celsius introduced his temperature scale, but with a surprising twist—it was upside down! He originally set 100° as the freezing point of water and 0° as its boiling point.

It was only after his death that the scale was flipped to the familiar version we use today, making it far more logical. This change is often credited to fellow scientist Carl Linnaeus.

How to Convert Celsius to Fahrenheit and Kelvin

Because Celsius is a global standard, knowing how to convert it to other scales, such as Fahrenheit (°F) and Kelvin (K), is useful. Here are the simple formulas to do it:

• Celsius to Fahrenheit (°F):
  • Formula: °F = (°C × 9/5) + 32
  • This scale is primarily used in the United States. For example, a pleasant 20 °C day is 68 °F.
• Celsius to Kelvin (K):
  • Formula: K = °C + 273.15
  • Kelvin is the official SI base unit for temperature and is mainly used in science. Note that Kelvin does not use the "degree" symbol.

What is the metric system?

Kelvin to degree Celsius Conversion Table

Here are some quick reference conversions from Kelvin (K) to degree Celsius (C):