Convert Temperature from Degree Rankine to Kelvin (R to K)

degree Rankine to Kelvin Conversion Formula

To convert from degree Rankine (R) to Kelvin (K), use the following formula:

Example

Let's convert 5 degree Rankine (R) to Kelvin (K).

Using the formula:

Therefore, 5 degree Rankine (R) is equal to $2.7777777777777777778$ Kelvin (K).

What Is the Rankine Temperature Scale (°R)?

The Rankine scale (°R) is a temperature measurement system built on absolute zero, much like the Kelvin scale. However, Rankine is specifically designed to work with the Fahrenheit system. Think of it as the Fahrenheit version of Kelvin, used primarily by engineers in the United States.

Why Is Rankine an Absolute Temperature Scale?

The Rankine scale is an absolute temperature scale, meaning its starting point—0 °R—is absolute zero. This is the coldest possible temperature in the universe, where all atomic and molecular motion stops completely.

Unlike scales such as Celsius and Fahrenheit, which have arbitrary zero points, absolute scales begin at true zero. This distinction is vital in science and engineering, particularly when a calculation requires dividing one temperature by another.

How to Convert Fahrenheit to Rankine

Since Fahrenheit and Rankine share the same degree size, a change of 1°F is equivalent to a shift in 1°R.

To convert Fahrenheit (°F) to Rankine (°R), add 459.67 to the Fahrenheit value.

Formula: °R = °F + 459.67

Example: Water freezes at 32 °F. To find this on the Rankine scale, you would calculate: 32 + 459.67 = 491.67 °R

Rankine is an Absolute Temperature Scale

The Rankine scale is an absolute temperature scale that is comparable to the Kelvin scale. Its zero point, 0 °R, represents absolute zero, which is the theoretical temperature where all molecular movement comes to a halt.

Unlike relative scales such as Fahrenheit or Celsius, which have arbitrary zero points (like the freezing point of water), Rankine starts from a true fundamental zero.

Where Is the Rankine Scale Used?

You will almost exclusively find the Rankine scale in engineering and thermodynamics fields within the United States.

Many scientific laws, especially those related to gases and energy efficiency (such as the Ideal Gas Law), require an absolute temperature to yield accurate results.

Rankine allows engineers working with imperial units (feet, pounds, Fahrenheit) to perform these critical calculations without first converting everything to Kelvin, which is the absolute scale for the metric system. It streamlines their workflow by keeping all units consistent.

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 the imperial system?

What is the metric system?

degree Rankine to Kelvin Conversion Table

Here are some quick reference conversions from degree Rankine (R) to Kelvin (K):