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Rankine to Kelvin Converter
↔ Convert K to °R instead

Common Conversions

°R K
0 0
90 50
180 100
360 200
491.67 273.15
536.67 298.15
540 300
671.67 373.15
720 400
900 500
1800 1000
9000 5000

Why this conversion matters in chemistry

Both scales start at absolute zero. The only difference is degree size: a Rankine equals a Fahrenheit, a Kelvin equals a Celsius. Dividing by 1.8 converts between them with no offset needed. The conversion comes up most when US-tradition engineering data — heat-exchanger correlations, gas-property tables, refinery process design — has to feed into a chemistry calculation written in SI. A 760 °R distillation-column bottom converts to 422.2 K, the value an Antoine-equation fit with SI-tabulated constants actually wants on its right-hand side.

Formula

K = °R / 1.8

Worked Examples

491.67 °R = 273.15 K

The freezing point of water — a fixed calibration anchor in both absolute scales.

0 °R = 0 K

Absolute zero — the shared origin of Rankine and Kelvin, by construction.

536.67 °R = 298.15 K

Standard reference temperature, 25 °C — the value behind tabulated standard-state thermodynamic data.

671.67 °R = 373.15 K

The normal boiling point of water at 1 atm — another shared calibration point of the two scales.

Frequently Asked Questions

How do I convert Rankine to Kelvin?
Divide by 1.8, or equivalently multiply by 5/9. So 540 °R becomes 300 K. Both scales share absolute zero, so no offset enters — just a rescaling of degree size.
Why would a chemist need this conversion?
When working from US engineering thermodynamic references — petroleum, natural gas, refinery property data — that report temperatures in Rankine. Almost every chemistry calculation downstream wants the temperature in Kelvin.
Is Rankine still used in modern chemistry?
Rarely in research literature, but it persists in US engineering applications, older industrial references, and the natural-gas sector. Kelvin is the SI standard and the default for any chemistry equation written today.
What gas-constant value uses Rankine?
R = 1.986 BTU/(lb-mol·°R) and R = 10.73 psi·ft³/(lb-mol·°R). Converting back to Kelvin lets you use the more familiar R = 8.314 J/(mol·K) or R = 0.08206 L·atm/(mol·K) — with the rest of the calculation already in SI.