Convert Rankine to Kelvin
Instantly convert Rankine (°R) to Kelvin (K) with our free online calculator.
Formula: °R to K — °R × 5/9
Reference Table
| Rankine (°R) | Kelvin (K) |
|---|---|
| 1 | 0.555556 |
| 5 | 2.77778 |
| 10 | 5.55556 |
| 25 | 13.8889 |
| 50 | 27.7778 |
| 100 | 55.5556 |
How to Convert Rankine to Kelvin
Formula
To convert Rankine (°R) to Kelvin (K): °R × 5/9
Step-by-Step
- Start with your value in Rankine (°R).
- °R × 5/9 to perform the conversion.
- The result is your value expressed in Kelvin (K).
Conversion Factor
1 °R = 0.555556 K
Reverse Factor
1 K = 1.8 °R
Worked Example
Convert 25 Rankine to Kelvin: 25 °R = 13.8889 K
About Rankine (°R)
An absolute temperature scale proposed by Scottish engineer William John Macquorn Rankine in 1859, using the Fahrenheit degree interval but anchored at absolute zero (0 °R = -459.67 °F = -273.15 °C = 0 K). Rankine is primarily used in US mechanical engineering for: combustion analysis (adiabatic flame temperatures, gas-turbine cycle inlet/outlet conditions), HVAC psychrometrics (the moist-air enthalpy formulation in ASHRAE Handbook chapter 1 sometimes uses °R for ideal-gas-mixture analysis), rocket propulsion (specific impulse Isp = thrust/mass-flow × g, where chamber temperatures are 5,000-6,500 °R for hydrocarbon-oxidizer systems and 6,000-7,500 °R for hydrogen-oxygen Space Shuttle Main Engine), and steam-cycle calculations per US-edition Cengel-Boles + Moran-Shapiro thermodynamics textbooks. Rankine is the temperature analog of US Customary engineering units the way kelvin is the metric equivalent — every dimensional-analysis problem involving ft-lbf, BTU, lbm, lbf, slug, and °F absolute requires °R to maintain coherence. Standard reference values: triple-point of water 491.69 °R; ICE standard ambient T 536.67 °R (= 25 °C); steam boiling 671.67 °R (= 100 °C). Most US engineering textbooks dual-list Kelvin and Rankine in thermodynamic tables.
About Kelvin (K)
The SI base unit of temperature per ISO 80000-5 §5-1, measured on an absolute scale where 0 K is absolute zero — the theoretical point at which all classical thermal motion stops (zero-point quantum motion remains). Named after Belfast-born British physicist William Thomson, 1st Baron Kelvin (1824-1907), whose 1848 paper 'On an Absolute Thermometric Scale' established the absolute-temperature concept. Redefined in 2019 BIPM SI revision by fixing the Boltzmann constant k_B = 1.380649 × 10⁻²³ J/K exactly. Kelvin shares its degree interval with Celsius (1 K = 1 °C, but offset by 273.15: 0 °C = 273.15 K), so conversion is a straight addition. Scientific publications, thermodynamic state-function math (entropy ds, free energy dG = dH - T·dS — requires absolute temperature), cryogenic physics (liquid helium boils at 4.2 K, liquid nitrogen at 77.4 K, dry ice CO₂ sublimes at 195 K), color temperature in photography and lighting (incandescent 2,700-3,000 K, daylight 5,500-6,500 K, blue sky 10,000-15,000 K), stellar surface temperatures (Sun 5,778 K; Sirius 9,940 K; Betelgeuse 3,500 K), and plasma physics (fusion plasma 10⁸ K) all use kelvin because absolute-zero-referenced math stays dimensionally clean.
Quick Facts
- 1 Rankine equals 0.555556 Kelvin
- 1 Kelvin equals 1.8 Rankine
- Rankine is a unit of temperature
- Kelvin is a unit of temperature
- This conversion is commonly used in weather forecasting, cooking, scientific experiments, and HVAC
- The Rankine belongs to the imperial system
- The Kelvin belongs to the metric system
Common Rankine to Kelvin Conversions
| Rankine (°R) | Kelvin (K) |
|---|---|
| -40 | -22.2222 |
| -20 | -11.1111 |
| -10 | -5.55556 |
| 0 | -5.684342e-14 |
| 5 | 2.77778 |
| 10 | 5.55556 |
| 15 | 8.33333 |
| 20 | 11.1111 |
| 25 | 13.8889 |
| 30 | 16.6667 |
| 35 | 19.4444 |
| 37 | 20.5556 |
| 40 | 22.2222 |
| 50 | 27.7778 |
| 60 | 33.3333 |
| 70 | 38.8889 |
| 80 | 44.4444 |
| 90 | 50 |
| 100 | 55.5556 |
| 150 | 83.3333 |
| 200 | 111.111 |
Understanding Rankine
The Rankine (symbol: °R) is a unit of temperature. An absolute temperature scale proposed by Scottish engineer William John Macquorn Rankine in 1859, using the Fahrenheit degree interval but anchored at absolute zero (0 °R = -459.67 °F = -273.15 °C = 0 K). Rankine is primarily used in US mechanical engineering for: combustion analysis (adiabatic flame temperatures, gas-turbine cycle inlet/outlet conditions), HVAC psychrometrics (the moist-air enthalpy formulation in ASHRAE Handbook chapter 1 sometimes uses °R for ideal-gas-mixture analysis), rocket propulsion (specific impulse Isp = thrust/mass-flow × g, where chamber temperatures are 5,000-6,500 °R for hydrocarbon-oxidizer systems and 6,000-7,500 °R for hydrogen-oxygen Space Shuttle Main Engine), and steam-cycle calculations per US-edition Cengel-Boles + Moran-Shapiro thermodynamics textbooks. Rankine is the temperature analog of US Customary engineering units the way kelvin is the metric equivalent — every dimensional-analysis problem involving ft-lbf, BTU, lbm, lbf, slug, and °F absolute requires °R to maintain coherence. Standard reference values: triple-point of water 491.69 °R; ICE standard ambient T 536.67 °R (= 25 °C); steam boiling 671.67 °R (= 100 °C). Most US engineering textbooks dual-list Kelvin and Rankine in thermodynamic tables.
It belongs to the imperial measurement system.
Rankine are commonly used in weather forecasting, cooking, scientific experiments, and HVAC.
Understanding Kelvin
The Kelvin (symbol: K) is a unit of temperature. The SI base unit of temperature per ISO 80000-5 §5-1, measured on an absolute scale where 0 K is absolute zero — the theoretical point at which all classical thermal motion stops (zero-point quantum motion remains). Named after Belfast-born British physicist William Thomson, 1st Baron Kelvin (1824-1907), whose 1848 paper 'On an Absolute Thermometric Scale' established the absolute-temperature concept. Redefined in 2019 BIPM SI revision by fixing the Boltzmann constant k_B = 1.380649 × 10⁻²³ J/K exactly. Kelvin shares its degree interval with Celsius (1 K = 1 °C, but offset by 273.15: 0 °C = 273.15 K), so conversion is a straight addition. Scientific publications, thermodynamic state-function math (entropy ds, free energy dG = dH - T·dS — requires absolute temperature), cryogenic physics (liquid helium boils at 4.2 K, liquid nitrogen at 77.4 K, dry ice CO₂ sublimes at 195 K), color temperature in photography and lighting (incandescent 2,700-3,000 K, daylight 5,500-6,500 K, blue sky 10,000-15,000 K), stellar surface temperatures (Sun 5,778 K; Sirius 9,940 K; Betelgeuse 3,500 K), and plasma physics (fusion plasma 10⁸ K) all use kelvin because absolute-zero-referenced math stays dimensionally clean.
It belongs to the metric measurement system.
Kelvin are commonly used in weather forecasting, cooking, scientific experiments, and HVAC.
Why Convert Rankine to Kelvin?
Converting between Rankine and Kelvin is essential for a variety of everyday and professional tasks. International recipes list oven temperatures in different scales, weather reports from other countries use unfamiliar units, and scientists must reconcile data recorded under different conventions. Medical professionals also compare body temperature readings that may be reported in different units depending on the country or device.
Frequently Asked Questions
How do I convert Rankine to Kelvin?
An absolute temperature scale proposed by Scottish engineer William John Macquorn Rankine in 1859, using the Fahrenheit degree interval but anchored at absolute zero (0 °R = -459. To convert Rankine to Kelvin, °R × 5/9. For example, 25 °R equals 13.8889 K.
How many Kelvin are in 1 Rankine?
There are 0.555556 Kelvin in 1 Rankine.
How many Rankine are in 1 Kelvin?
There are 1.8 Rankine in 1 Kelvin.
What is the formula for Rankine to Kelvin conversion?
The formula is: °R × 5/9. This means 1 °R = 0.555556 K.
Is a Rankine bigger than a Kelvin?
Yes. One Rankine is larger than one Kelvin because 1 °R equals 0.555556 K, which is less than 1.
When do you need to convert between Rankine and Kelvin?
The SI base unit of temperature per ISO 80000-5 §5-1, measured on an absolute scale where 0 K is absolute zero — the theoretical point at which all classical thermal motion stops (zero-point quantum motion remains). Rankine and Kelvin are both temperature units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.