The purpose of this standard is to establish the equations for calculating the potential composition of Portland clinker, based on the results of its chemical analysis carried out according to the UNE 80-215 standard. The potential composition, in turn, aims to express, in an approximate way, the way in which the main oxides of the clinker, determined analytically, are most likely combined to form the main mineralogical species of the same, that is, the silicates, aluminates and calcium ferrites.