How do you convert Rankine to Celsius?

Use the formula: °C = (°R − 491.67) × 5/9. Enter your Rankine value into the converter and it will calculate Celsius instantly.

Why is there 491.67 in the formula?

Rankine and Fahrenheit share the same degree size. Absolute zero is 0 R and −459.67 °F. Celsius is offset by 273.15 K, so when you combine the offsets you get 491.67 in the Rankine-to-Celsius formula.

Can I also get Kelvin and Fahrenheit from Rankine?

Yes. 1 K = 1.8 °R, so K = °R × 5/9. Fahrenheit = °R − 459.67. This tool shows all 4 temperature scales at once.

Rankine to Celsius Converter (°R ⇄ °C)

Quick table (Rankine → Celsius)

Rankine (°R)	Celsius (°C)	Kelvin (K)	Notes
0	−273.15	0	Absolute zero
491.67	0	273.15	Freezing point water
671.67	100	373.15	Boiling water (approx.)
540			Example process

How the conversion works

Rankine → Celsius

°C = (°R − 491.67) × 5/9

Celsius → Rankine

°R = (°C + 273.15) × 9/5

Rankine → Kelvin

K = °R × 5/9

Rankine → Fahrenheit

°F = °R − 459.67

Why is Rankine used?

Rankine appears in older US thermodynamics, aerospace, and some HVAC documentation because it keeps the Fahrenheit-size degree but starts at absolute zero. This makes many gas-law equations simpler while staying in “Fahrenheit-like” units.

FAQ

1. Is Rankine the same as Kelvin?

Not quite. Both are absolute scales, but a Rankine degree is 1.8 times larger than a Kelvin. To go from Rankine to Kelvin, multiply by 5/9.

2. I have °F — can I still use this?

Yes. First change °F to °R by adding 459.67, then use the Rankine → Celsius formula: °C = (°R − 491.67) × 5/9.

3. Do I need more decimals?

For engineering work, yes, especially near 491.67 °R, because small mistakes in the offset can shift Celsius by tenths of a degree. The calculator above already uses the precise constants.