Convert Pound-force Feet per Pound per °R to Joules per Kilogram per Kelvin
Pound-force Foot per Pound per °R (lbf·ft/(lb·°R)) to Joule per Kilogram per Kelvin (J/(kg·K)) specific heat capacity conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 lbf·ft/(lb·°R) = 5.3803205 J/(kg·K)
1 Pound-force Foot per Pound per °R = 5.3803205 Joules per Kilogram per Kelvin
1 Joule per Kilogram per Kelvin = 0.18586254 Pound-force Feet per Pound per °R
1 lbf·ft/(lb·°R) in every supported unit
Conversion chart: Pound-force Foot per Pound per °R to Joules per Kilogram per Kelvin
Conversion table
| Pound-force Foot per Pound per °R (lbf·ft/(lb·°R)) | Joule per Kilogram per Kelvin (J/(kg·K)) |
|---|---|
| 0.01 lbf·ft/(lb·°R) | 0.053803205 J/(kg·K) |
| 0.1 lbf·ft/(lb·°R) | 0.53803205 J/(kg·K) |
| 1 lbf·ft/(lb·°R) | 5.3803205 J/(kg·K) |
| 2 lbf·ft/(lb·°R) | 10.760641 J/(kg·K) |
| 3 lbf·ft/(lb·°R) | 16.140961 J/(kg·K) |
| 5 lbf·ft/(lb·°R) | 26.901602 J/(kg·K) |
| 10 lbf·ft/(lb·°R) | 53.803205 J/(kg·K) |
| 20 lbf·ft/(lb·°R) | 107.60641 J/(kg·K) |
| 50 lbf·ft/(lb·°R) | 269.01602 J/(kg·K) |
| 100 lbf·ft/(lb·°R) | 538.03205 J/(kg·K) |
| 1000 lbf·ft/(lb·°R) | 5380.3205 J/(kg·K) |
Pound-force Foot per Pound per °R (lbf·ft/(lb·°R))
Definition: The US customary mechanical-work equivalent of specific heat capacity — pound-force feet of work per pound of mass per degree Rankine, the imperial counterpart to kilogram-force meter per kilogram per kelvin.
History: Rooted in the US customary "gravitational" unit system that used pound-force as a base force unit, paired with the absolute Rankine temperature scale for thermodynamic consistency.
Current use: Rare today, found mainly in older US thermodynamics and mechanical engineering textbooks that predate the shift to SI-based specific heat reporting.
Joule per Kilogram per Kelvin (J/(kg·K))
Definition: The SI derived unit of specific heat capacity — the joules of energy needed to raise the temperature of one kilogram of a substance by one kelvin.
History: Formed directly from the joule, kilogram, and kelvin once all three were standardized as SI units, giving thermodynamics a single coherent unit consistent with all other SI energy and mass calculations.
Current use: The standard unit in physics, chemistry, and engineering thermodynamics worldwide for comparing how much energy different materials store per degree of heating.
Supported Units
| Unit | Symbol | In J/(kg·K) |
|---|---|---|
| Joule per Kilogram per Kelvin | J/(kg·K) | 1 J/(kg·K) |
| Kilojoule per Kilogram per Kelvin | kJ/(kg·K) | 1000 J/(kg·K) |
| Joule per Gram per °C | J/(g·°C) | 1000 J/(kg·K) |
| Calorie (IT) per Gram per °C | cal/(g·°C) | 4186.8 J/(kg·K) |
| Kilocalorie (IT) per Kilogram per °C | kcal/(kg·°C) | 4186.8 J/(kg·K) |
| Btu (IT) per Pound per °F | Btu/(lb·°F) | 4186.8 J/(kg·K) |
| Btu (IT) per Pound per °C | Btu/(lb·°C) | 2326 J/(kg·K) |
| Kilogram-force Meter per Kilogram per Kelvin | kgf·m/(kg·K) | 9.80665 J/(kg·K) |
| Pound-force Foot per Pound per °R | lbf·ft/(lb·°R) | 5.3803205 J/(kg·K) |
About These Parameters
- Value
- The specific heat capacity value you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — a chemistry reference's cal/(g·°C), or a US engineering datasheet's Btu/(lb·°F).
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Specific Heat Capacity Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to joules per kilogram per kelvin. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Pound-force Foot per Pound per °R → Joule per Kilogram per Kelvin: multiply by 5.3803205. For example, 1 lbf·ft/(lb·°R) × 5.3803205 = 5.3803205 J/(kg·K).
Q = mcΔT
Specific heat capacity (c) is the key figure in the fundamental heat-energy equation Q = mcΔT — the heat energy Q needed equals mass (m) times specific heat capacity (c) times the temperature change (ΔT). This is the formula behind everything from calculating how much energy it takes to boil a kettle of water to sizing an industrial heat exchanger.
Why Water Is the Reference Point
Water has an unusually high specific heat capacity (about 4,186 J/(kg·K), or almost exactly 1 cal/(g·°C) by the calorie's original definition) compared to most other everyday materials — metals typically sit between 100 and 900 J/(kg·K). This is why large bodies of water moderate coastal climates, why water is used as a coolant in engines and power plants, and why the calorie and Btu, both originally water-based reference units, come out so close to a value of 1 on this page's water-referenced units.
Example
A specific heat capacity of 1 lbf·ft/(lb·°R) equals 5.3803205 J/(kg·K). For scale, water's specific heat capacity is about 4,186 J/(kg·K) (1 cal/(g·°C)), while aluminum's is about 897 J/(kg·K) — meaning it takes roughly 4.7 times more energy to heat a kilogram of water by one degree than the same mass of aluminum.
Frequently Asked Questions
How many Joules per Kilogram per Kelvin are in 1 Pound-force Foot per Pound per °R?
1 Pound-force Foot per Pound per °R (lbf·ft/(lb·°R)) equals exactly 5.3803205 Joules per Kilogram per Kelvin (J/(kg·K)).
Why is water's specific heat capacity almost exactly 1 cal/(g·°C)?
It's not a coincidence — the calorie was originally DEFINED in the 19th century as the energy needed to raise one gram of water by one degree Celsius. The modern International Table calorie is now fixed to a precise joule value rather than redefined by experiment each time, which is why the figure comes out extremely close to, but not perfectly, 1.
What's the difference between specific heat capacity and heat capacity?
Specific heat capacity is a per-unit-mass property of a substance (energy per kg per degree), independent of how much of the substance you have. Heat capacity (without "specific") is the total energy needed to heat a particular object or quantity by one degree, found by multiplying specific heat capacity by the actual mass involved.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying energy, mass, and temperature units (e.g. 1 cal (IT) = exactly 4.1868 joules) — results are limited only by floating-point display precision, not by rounded conversion constants.