# Gibbs free energy calculator

## Description

The Gibbs free energy is a thermodynamic potential that measures the “usefulness” or process-initiating work obtainable from a thermodynamic system at a constant temperature and pressure (isothermal, isobaric). When a system changes from a well-defined initial state to a well-defined final state, the Gibbs free energy ΔG equals the work exchanged by the system with its surroundings, minus the work of the pressure forces, during a reversible transformation of the system from the same initial state to the same final state.

Related formulas## Variables

G | Free energy (J) |

U | Internal energy (J) |

p | Pressure (Pa) |

V | Volume (m^{3}) |

T | Temperature (K) |

S | Entropy (J/K) |