Gibbs Free Energy Calculator
ΔG from enthalpy, temperature and entropy — with spontaneity.
Enter your values
Enter the enthalpy change δh in kJ/mol.
Enter the temperature in K.
Enter the entropy change δs in J/mol·K.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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
At a glance
| What it does | ΔG from enthalpy, temperature and entropy — with spontaneity. |
|---|---|
| Category | Chemistry |
| Inputs needed | Enthalpy change ΔH, Temperature, Entropy change ΔS |
| Main output | ΔG |
| Formula | ΔG = ΔH − TΔS |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Enthalpy change ΔH(kJ/mol)
- Enter the enthalpy change δh in kJ/mol.
- Temperature(K)
- Enter the temperature in K.
- Entropy change ΔS(J/mol·K)
- Enter the entropy change δs in J/mol·K.
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.
What do I need to enter into the Gibbs Free Energy Calculator?
Just 3 values: enthalpy change δh, temperature, entropy change δs. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Gibbs Free Energy Calculator work out the answer?
Gibbs free energy is ΔG = ΔH − TΔS. A negative ΔG means the reaction is spontaneous at that temperature. It applies the formula ΔG = ΔH − TΔS and shows the working so you can check each step by hand.
Is the Gibbs Free Energy Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.