Gibbs Free Energy Calculator
Calculate Gibbs free energy from enthalpy, entropy, and temperature.
Gibbs Free Energy measurements
Enter your values, then calculate.
Result
How to calculate gibbs free energy
This calculator finds Gibbs free energy change from enthalpy, temperature, and entropy — determining whether a reaction is thermodynamically favorable.
How the calculation works
ΔG = ΔH − TΔS ÷ 1000, where ΔH is in kJ/mol, T is in Kelvin, and ΔS is in J/(mol·K) (divided by 1000 to convert to kJ for consistent units with ΔH).
Example
ΔH = −40 kJ/mol, T = 298K, ΔS = −50 J/(mol·K): −40 − (298×(−50)÷1000) = −40−(−14.9) = −25.1 kJ/mol.
Frequently asked questions
How is Result calculated?
Result = [Enthalpy change] − [Temperature] × [Entropy change] ÷ 1000.
Is the Gibbs Free Energy Calculator free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Gibbs Free Energy Calculator
ΔG = ΔH − TΔS ÷ 1000, where ΔH is in kJ/mol, T is in Kelvin, and ΔS is in J/(mol·K) (divided by 1000 to convert to kJ for consistent units with ΔH).
Let's understand your gibbs free energy result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Gibbs Free Energy
- A negative ΔG indicates a spontaneous (thermodynamically favorable) reaction under the given conditions; positive means non-spontaneous.
- Temperature must be in Kelvin, and watch unit consistency between ΔH (kJ/mol) and ΔS (J/mol·K).
Common Gibbs Free Energy Mistakes to Avoid
- Forgetting to convert ΔS from J/(mol·K) to kJ/(mol·K) before combining with ΔH in kJ/mol, which introduces a factor-of-1000 error.
When to Use This Calculator
This calculator finds Gibbs free energy change from enthalpy, temperature, and entropy — determining whether a reaction is thermodynamically favorable.