Gibbs Free Energy Calculator — ΔG = ΔH − TΔS

Gibbs free energy weighs a reaction's heat release against its entropy cost. A negative ΔG means the reaction can proceed spontaneously at that temperature — this tool computes it and lets you solve for any of the three inputs.

How to interpret the result

Worked check: formation of liquid water, ΔH = −285.8 kJ/mol, ΔS = −163.2 J/(mol·K), T = 298 K → ΔG = −285800 − 298×(−163.2) = −237166 J ≈ −237.2 kJ/mol, spontaneous. Note the entropy unit (J/K) is a thousand times smaller than kJ — the tool handles that.

Assumptions

• ΔH and ΔS are approximately temperature-independent
• Standard-state values; temperature in kelvin