Abstract: The method for air classification of toner used to develop electrostatic images, whereby a toner product consisting of a powder with a wide particle size distribution is converted into a higher-quality toner product with a narrow particle size distribution in that the residence time of the toner product is controlled by means of components, components which in the upper section of the classifying chamber quickly introduce the toner product in a homogeneous state into the classifying chamber, which in the central section of the classifying chamber permit a longer residence time of the toner product, and which in the bottom section of the classifying chamber permit rapid discharge of the toner product from the classifying chamber, all of which makes it possible to produce a toner end product with an extremely narrow particle size distribution.