Convert Rankine to Kelvin

To convert Rankine (°R) to Kelvin (K), use a simple scale change. Both scales start at absolute zero, but Rankine uses Fahrenheit-sized degrees.

• Formula (Rankine to Kelvin): K = °R ÷ 1.8
• Same formula, simpler form: K = °R × (5/9)

Example:
If °R = 540, then K = 540 ÷ 1.8 = 300 K.

Use this conversion any time you need to change °R to K in science, engineering, or thermodynamics.

What is the Rankine to Kelvin conversion?

Rankine (°R) and Kelvin (K) are both absolute temperature scales. That means they start at absolute zero. The Rankine scale uses the same size degree as Fahrenheit, while Kelvin uses the same size degree as Celsius.

To convert Rankine to Kelvin, you scale by the ratio between Fahrenheit and Celsius degree sizes.

What is the formula to convert Rankine to Kelvin?

Use this formula:

• K = °R × 5/9

This works because a Rankine degree is larger than a Kelvin by a factor of 9/5.

How do you convert Rankine to Kelvin step by step?

1. Take the temperature in Rankine (°R).
2. Multiply it by 5.
3. Divide the result by 9.
4. The final value is Kelvin (K).

It’s a direct conversion with no offsets.

What is 0 Rankine in Kelvin?

• 0 °R = 0 K

Both scales start at absolute zero, so zero Rankine equals zero Kelvin.

What is 491.67 Rankine in Kelvin?

• 491.67 °R = 273.15 K

This value matches the freezing point of water, which is 273.15 K.

What is 671.67 Rankine in Kelvin?

• 671.67 °R = 373.15 K

This is the boiling point of water at standard pressure, which is 373.15 K.

Why is Rankine converted to Kelvin by multiplying by 5/9?

Rankine is tied to Fahrenheit degree size. Kelvin is tied to Celsius degree size. One Celsius degree equals 1.8 Fahrenheit degrees. So converting an absolute Fahrenheit-based scale to an absolute Celsius-based scale uses 5/9 to shrink the step size.

Do you add or subtract anything when converting Rankine to Kelvin?

No. You only multiply by 5/9.

Unlike Fahrenheit to Celsius, there is no need to add or subtract 32. Both Rankine and Kelvin already begin at absolute zero.

Is Kelvin ever written with a degree symbol?

No. Kelvin is written as K, not °K.

Rankine is often written as °R.

Can Kelvin values be negative after converting from Rankine?

No. Rankine can’t go below 0 °R. Kelvin can’t go below 0 K. If you see a negative result, the input or the math is wrong.

How do you convert Kelvin back to Rankine?

Use the reverse formula:

• °R = K × 9/5

This expands the Kelvin step size to match Rankine.

What is the relationship between Rankine, Kelvin, Fahrenheit, and Celsius?

Rankine and Kelvin are absolute scales. Fahrenheit and Celsius are relative scales with different zero points.

Common links:

• °R = °F + 459.67
• K = °C + 273.15
• K = (°F + 459.67) × 5/9
• K = °R × 5/9

What units are used with Rankine and Kelvin?

Both measure thermodynamic temperature. Kelvin is the SI base unit for temperature. Rankine is used less often, but you may see it in some engineering fields, especially when Fahrenheit-based units appear in formulas.

What are common mistakes in Rankine to Kelvin conversion?

Common errors include:

• Using °C to K rules (adding 273.15) by mistake.
• Using 9/5 instead of 5/9.
• Mixing up Fahrenheit and Rankine, since they share degree size.
• Adding or subtracting 459.67 when it isn’t needed for °R to K.