Rankine to Kelvin
Free instant rankine to kelvin converter. 1 °R = 0.555556 K.
Common Rankine to Kelvin values
| Rankine (°R) | Kelvin (K) |
|---|---|
| -40 | -22.2222 |
| 0 | 0 |
| 10 | 5.55556 |
| 20 | 11.1111 |
| 25 | 13.8889 |
| 37 | 20.5556 |
| 100 | 55.5556 |
| 1000 | 555.556 |
How does Rankine to Kelvin conversion work?
Type a value in the Rankine (°R) field and the equivalent in Kelvin (K) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.
Rankine. A US-engineering absolute scale that uses Fahrenheit-sized degrees. 0 °R is absolute zero (= 0 K = −459.67 °F). Used in older HVAC, aerospace, and thermodynamics work.
Kelvin. The SI base unit for temperature, used in science. 0 K is absolute zero (−273.15 °C). No degree symbol — just "K".
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Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.
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How it works — the formula
F = C × 9/5 + 32
C = (F − 32) × 5/9
K = C + 273.15
C = K − 273.15Temperature scales are affine, not linear: they have both a slope and an offset because zero on one scale is not zero on another. Celsius and Fahrenheit share a slope ratio of 9:5 and intersect at −40° (where °C = °F). Kelvin uses the same magnitude as Celsius but its zero is absolute zero, the lowest physically possible temperature; the 2019 SI redefinition fixed the Boltzmann constant k = 1.380649 × 10⁻²³ J/K exactly.
Worked examples
- Inputs:
- 37 °C = ? °F
- Output:
- 37 × 9/5 + 32 = 98.6 °F
- Inputs:
- 0 °C, 100 °C → °F
- Output:
- 32 °F and 212 °F (definitions of the Fahrenheit scale)
- Inputs:
- −40 °C = ? °F
- Output:
- −40 °F (the unique fixed point where °C = °F)
Limitations
- Negative kelvin is unphysical — absolute zero (0 K = −273.15 °C) is the floor for ordinary thermodynamic temperature.
- Rankine (°R) is a US-engineering absolute scale (R = F + 459.67) sometimes seen in older HVAC / aerospace work.
- Wind chill, "feels-like" temperatures, and humidity-adjusted indices are NOT pure unit conversions — they are derived metrics with their own formulas.
- Above ~10⁹ K, plasma physics uses electronvolt as a temperature unit (1 eV ≈ 11,605 K) — out of scope for everyday converters.
Conversions are exact rational identities between Celsius/Fahrenheit/Kelvin; trailing-digit differences come from binary floating-point representation only.