AbstractMost existing theories of the response of electrical sensing zone particle size analysers, for instance of the type Coulter Counter®, predict that a significant deviation from sizing linearity will occur at and above some 40% of the aperture diameter. Practical experience, at least for the only test models available ‐ latex spheres ‐ shows that this is not the case in practice. Linear particle response up to 80% of the aperture diameter has been established, confirming the prediction recently made byScarlettin a new response th