Equilibrium Constant from Gibbs Energy Calculator

About this calculator

The Gibbs free energy change (ΔG) of a reaction and its equilibrium constant K are two ways of describing the same underlying thermodynamics, linked by ΔG = −RT·ln(K), where R is the gas constant and T is the absolute temperature. Rearranged to solve for K, this becomes K = exp(−ΔG / RT) — a negative ΔG (energy released) corresponds to K greater than 1, meaning products are favored at equilibrium, while a positive ΔG corresponds to K less than 1, favoring reactants.

This calculator computes K directly from a given ΔG and temperature, and reports whether the reaction is spontaneous under those conditions. It's a standard calculation in physical chemistry and biochemistry courses, and the same relationship underlies how chemists predict reaction extent, how biochemists analyze enzyme-catalyzed equilibria, and how process engineers estimate conversion yields before running a reaction.