Gibbs' Phase Rule Calculator
Enter the number of independent components (C) and the number of phases (P) present at equilibrium. The calculator applies Gibbs' phase rule, F = C − P + 2, to find the degrees of freedom.
Last updated: September 26, 2026
Frequently asked questions
What is Gibbs' phase rule?
It relates the number of independent components (C), the number of phases present at equilibrium (P), and the degrees of freedom (F) - the number of intensive variables, like temperature and pressure, that can be changed independently without changing the number of phases.
What counts as a component?
A component is an independently variable chemical species needed to describe the system's composition. For a single pure substance like water, C = 1. Mixtures generally have more components.
What counts as a phase?
A phase is a physically distinct, homogeneous part of the system, such as solid, liquid, and vapor. Water at its triple point has three phases coexisting (P = 3).
What does F = 0 mean?
It means the system is invariant: at a fixed set of conditions (like water's triple point), you can't change temperature or pressure at all without losing one of the coexisting phases.
Why did I get a negative or impossible result?
A negative F under this basic form of the rule usually means too many phases are claimed to coexist for the given number of components - check whether your phase and component counts are consistent with an equilibrium system.
Is this the same as Gibbs Free Energy?
No, despite sharing the name Gibbs. The phase rule is about how many phases can coexist and how many variables you can independently adjust. Gibbs free energy is about a system's thermodynamic favorability and spontaneity. They're related areas of thermodynamics but answer different questions.