Bond standard procedures are often used in design of comminution circuits, especially in the case of ball mill grinding circuits. Although it is usually considered as an industry standard, its procedure was not fully defined by Fred Bond, and sometimes sensible variations in test results can be obtained due to some undefined steps in the method. This is the case of the calculation of characteristic size in product (P-80), which must be calculated through interpolation using some PSD (particle size distribution) function and Bond's procedure did not establish the way to perform this calculation. The purpose of this technical note is to outline an evaluation of the adjustment quality of different distribution models in order to determine P-80 in Bond's ball mill test. (C) 2016 Elsevier B.V. All rights reserved.