Convert Joules per Kilogram-Kelvin to Calories per Gram-Celsius

The Joule per Kilogram-Kelvin (symbol: J/(kg·K)) is a unit of specific entropy. The SI unit of specific entropy (entropy per unit mass) per ISO 80000-5 §5-19.1 — used in steady-flow thermodynamics where the relevant entropy quantity is normalized to the mass flow rate through a control volume (nozzles, turbines, compressors, heat exchangers). J/(kg·K) is the universal output unit for computational thermodynamics libraries: CoolProp (open-source Helmholtz-energy-based property library), NIST REFPROP (the gold-standard reference fluid property database), IAPWS-IF97 industrial-formulation steam tables, and commercial process simulators (Aspen Plus, ChemCAD, HYSYS, ProMax). Dimensionally identical to specific heat capacity c_p in J/(kg·K), but physically distinct — entropy is a state function representing energy spreading, while c_p is a heat-flow response coefficient. Reference values per IAPWS-IF97: liquid water at 25°C has s ≈ 367 J/(kg·K); steam at 200°C and 1 bar has s ≈ 7,834 J/(kg·K); R-134a saturated vapor at 25°C has s ≈ 1,718 J/(kg·K); dry air at 25°C and 1 bar has s ≈ 6,876 J/(kg·K) (relative to reference state). Used universally in CFD strong-form energy-equation post-processing (ANSYS Fluent, OpenFOAM, STAR-CCM+).

It belongs to the metric measurement system.

Joules per Kilogram-Kelvin are commonly used in turbine design, refrigeration analysis, and power plant engineering.

The Calorie per Gram-Celsius (symbol: cal/(g·°C)) is a unit of specific entropy. A CGS specific-entropy unit numerically identical to kcal/(kg·°C) and equal to 4,184 J/(kg·K) (using the thermochemical calorie). cal/(g·°C) appears in older chemistry literature for solution-calorimetry data (heats of dissolution, mixing, dilution), biological thermodynamics where the energy-scale is naturally small (protein unfolding ΔS ≈ 0.5 cal/(g·°C); ligand-receptor binding entropy in isothermal titration calorimetry; lipid-bilayer phase transitions), legacy food-science publications (specific heats of water = 1.000 cal/(g·°C) by historical definition), and pharmaceutical-formulation papers measuring excipient thermal properties via differential scanning calorimetry (DSC). The unit's persistence is due to the historical definition of the calorie as exactly the heat required to raise 1 g of water by 1 °C between 14.5°C and 15.5°C (giving water's specific heat the convenient value of 1.000 in this unit system). Mostly superseded by SI J/(kg·K) or kJ/(kg·K) in modern publications, but cal/(g·°C) still appears in NIST WebBook cross-references, in older Russian and German thermochemistry compilations (Landolt-Börnstein), and in TA Instruments and PerkinElmer DSC software output options.

It belongs to the metric measurement system.

Calories per Gram-Celsius are commonly used in turbine design, refrigeration analysis, and power plant engineering.