Unit Conversion

Convert numbers between two units quickly and precisely

Entropy

Unit Conversion

Convert entropy units: joule per kelvin, kilojoule per kelvin, and calorie per kelvin

Entropy is a measure of disorder in a thermodynamic system and is stated in joule per kelvin (J/K), the SI unit, as well as kilojoule per kelvin (kJ/K) and the older unit calorie per kelvin (cal/K). The entropy converter accurately converts between these three units.

Key conversion factors:

  • 1 kilojoule per kelvin (kJ/K) = 1,000 joule per kelvin (J/K)
  • 1 calorie per kelvin (cal/K) = 4.184 joule per kelvin

Applications:

  • Thermodynamics: entropy changes in chemical reactions and phase transitions
  • Physical chemistry: calculating free energy and equilibrium constants

The entropy converter supports thermodynamic calculations in chemistry and physics. To calculate ΔG from ΔH, ΔS, and T, use our Gibbs free energy calculator; for the relationship with the equilibrium constant K, use the equilibrium constant calculator.

Frequently asked questions about converting entropy

1 calorie per kelvin (cal/K) equals 4.184 joule per kelvin (J/K). This conversion matters when older thermodynamic reference tables give entropy values in calories instead of joules.

J/K is the unit of reaction entropy ΔS, which, together with reaction enthalpy ΔH and temperature T, enters the free energy of reaction ΔG via ΔG = ΔH - T*ΔS. It helps determine whether a reaction proceeds spontaneously.

Reference tables usually give standard entropies per mole, since entropy scales with the amount of substance in a reaction. This converter converts between the base units J/K, kJ/K, and cal/K – the conversion between total and molar quantities stays the same as long as you calculate consistently per mole.