The adsorption of polycyclic aromatic hydrocarbons on transition metal surfaces is of great interest to understand the possibility of their hydrogenation or their cracking in heterogeneous catalytic processes. In this paper, periodic density functional theory (DFT) calculations are presented for the comparison of the adsorption of benzene, naphthalene, and anthracene molecules on Pt(111) surfaces. For each molecule, the best adsorption structure is associated with aromatic rings on bridge sites, with increasing adsorption energies per molecule (-0.90, -1.37, and -1.79 eV, respectively), while the adsorption structures associated with aromatic rings on hollow sites are systematically less stable. Upon adsorption, molecules are distorted, which implies a modification of the energetic level and the shape of molecular orbitals, and hence ensures a better molecule-surface stabilizing interaction. The electronic analysis shows similar interactions between the molecule and the surface in each case. A model is proposed to determine the adsorption energy of larger aromatic polycyclic molecules, based on the estimation of the distortion energy of the molecule and surface, and of interaction energies between each aromatic ring and the surface.