Gibbs Free Energy Calculator

About this calculator

This calculator finds Gibbs free energy change, ΔG = ΔH − T·ΔS, which combines a reaction's enthalpy change ΔH (heat absorbed or released), absolute temperature T, and entropy change ΔS into a single value that predicts spontaneity at constant pressure and temperature. A negative ΔG means the reaction is spontaneous (exergonic) and can proceed on its own; a positive ΔG means it's non-spontaneous (endergonic) and needs energy input; ΔG is also linked to the equilibrium constant K through ΔG = −RT·ln K.

Chemists use this to predict whether a reaction will run forward under given conditions, biochemists use it to explain energy-coupling in metabolism — such as ATP hydrolysis driving otherwise unfavorable reactions — and chemical engineers use it to assess the feasibility and yield of industrial processes before committing to them. Chemistry and biochemistry students, researchers, and process engineers all rely on this calculation to connect thermodynamics to real reaction behavior.