Gibbs Free Energy Calculator
ΔG from enthalpy, temperature and entropy — with spontaneity.
Enter your values
ⓘ Live results
Results
- ΔG
- -32.987 kJ/mol
- Spontaneous?
- Yes — spontaneous
- TΔS term
- -59.213 kJ/mol
- Crossover temperature
- 464 K
Quick answer
Gibbs free energy is ΔG = ΔH − TΔS. A negative ΔG means the reaction is spontaneous at that temperature.
ΔG = ΔH − TΔS
How to use the Gibbs Free Energy Calculator
- 1Enter ΔH in kJ/mol.
- 2Enter the absolute temperature in kelvin.
- 3Enter ΔS in J/mol·K — the calculator converts it for you.
Worked example
Using the values the calculator loads with:
Inputs
- Enthalpy change ΔH-92.2 kJ/mol
- Temperature298 K
- Entropy change ΔS-198.7 J/mol·K
Results
- ΔG-32.987 kJ/mol
- Spontaneous?Yes — spontaneous
- TΔS term-59.213 kJ/mol
- Crossover temperature464 K
Frequently asked questions
What does a negative ΔG mean?
The reaction releases usable energy and proceeds spontaneously in the forward direction at that temperature.
Why divide ΔS by 1000?
ΔH is quoted in kJ/mol while ΔS is quoted in J/mol·K, so ΔS must be converted to kJ before subtracting.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.