Ionic micelles are typically very affected by the salt concentration. In ionic micelles the monomers are typically fully ionized, but the high electric field strength at the surface of the micelles will cause adsorption of some proportion of the free counter-ions. In this case a chemical equilibrium process can be assumed between the charged micelles  and its constituents, the bile salt monomers,  and bound counter-ions :
where  is the average aggregation number and  is the average degree of counter-ion binding to the micelle. In this case, the Gibbs free energy is given by:
where  is the Gibbs energy of micellization and  is the free counter-ion concentration at CMC. For large , that is in the limit when then the micelles becomes a true macroscopic phase, the Gibbs free energy is usually approximated by: