A method and device for forming a stack of n packets, whereby the packets, fed successively in a substantially horizontal direction to an input of a substantially vertical conveyor channel, are stacked by being lifted, along the conveyor channel, by an n-start screw push device rotating about an axis substantially parallel to the conveyor channel; the stack so formed is extracted from an output of the conveyor channel, in a radial output direction with respect to the axis of the screw push device, by a comb extractor movable along an annular path extending through the conveyor channel.