# Free Energy of Chemical Reaction Calculator

getcalc.com's **Gibb's Free Energy (G) Calculator** is an online chemical engineering tool to estimate the available energy of the chemical reaction, in both US customary & metric (SI) units.

## Definition & Formula

**Gibb's Free Energy**, often denoted by the alphabet G, also known as free enthalpy, gibbs function or gibbs energy, is a thermodynamic function represents the difference between enthalpy (H) and the the product of the temperature (Kelvin) and the entropy (S) of the system. The change of free energy ΔG measures the direction of chemical reaction under constant temperature or pressure, represents the difference between the change in enthalpy ΔH and the product of the temperature (Kelvin) and the change in the entropy ΔS of the system