To obtain a simulated adsorption isotherm using MTT, it is also necessary to estimate the area that each adsorbed molecule occupies on the surface. As explained by Nikas et al., several difficulties arise concerning the estimation of the hard-disk area of each molecule on the surface due to steric effects. For instance, this area depends on the molecular conformations accessible to the adsorbed surfactant, which will depend on the surface coverage. As a result, the effective cross-sectional area will be coverage-dependent. In practice, it is usually sufficient to estimate the hard-disk area at high concentration and thus high coverage, since this is where the steric repulsion of adsorbed molecules limits further increases to the surface coverage.