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Rankine to Celsius Converter
↔ Convert °C to °R instead

Common Conversions

°R °C
0 -273.15
100 -217.59
200 -162.04
300 -106.48
400 -50.93
491.67 0
500 4.63
536.67 25
600 60.19
671.67 100
800 171.3
1000 282.41

Why this conversion matters in chemistry

Rankine temperatures come out of US-spec thermodynamic references — combustion calculations, Rankine-cycle analyses, steam tables that never made the switch to SI. Celsius is the native scale for almost everything else in chemistry, from calorimetry to reaction kinetics to literature reaction temperatures. Subtracting 491.67 and multiplying by 5/9 is the step that moves a Rankine entry onto a metric data sheet. A 1000 °R boiler inlet, for instance, lands at 282.4 °C — close enough to the temperatures where high-temperature catalysis actually runs to be recognizable.

Formula

°C = (°R − 491.67) × 5/9

Worked Examples

491.67°R = 0°C

The Rankine value at the freezing point of water — the anchor point that defines the offset between the two scales.

671.67°R = 100°C

The boiling point of water at 1 atm, written in the units a US steam table would use.

536.67°R = 25°C

Standard reference temperature — the value behind tabulated ΔG° and most room-temperature thermochemistry.

0°R = -273.15°C

Absolute zero. Both Rankine and Kelvin bottom out here; only the degree size differs.

Frequently Asked Questions

How do I convert Rankine to Celsius?
Subtract 491.67, then multiply by 5/9. So 536.67 °R − 491.67 = 45, and 45 × 5/9 = 25 °C — the standard reference temperature in both scales.
What is the Rankine scale for?
Rankine is an absolute temperature scale with Fahrenheit-sized degrees, used in US engineering thermodynamics — combustion calculations, gas-turbine and steam-cycle analyses, and some property tables. It's the Fahrenheit counterpart to Kelvin.
What is 0 °R in Celsius?
Exactly −273.15 °C, which is absolute zero. Both Rankine and Kelvin start at absolute zero by construction; the only difference is that Rankine's degree is 5/9 the size of Kelvin's.
Where does a chemist bump into Rankine?
Older US engineering literature, high-temperature combustion chemistry, and thermodynamic property compilations that predate the SI switch. Any calculation anchored to those sources needs a conversion back to Celsius or Kelvin before it meets chemistry's own equations.