A square baler having a control system including at least one density sensor for measuring the relative density of crop slices within the intake duct and/or the intake region of the baling chamber. A correlation function is determined by correlating the measured relative density of slices in the intake duct and/or the intake region of the baling chamber with the cumulative weight of these slices after they have been compressed and bound to form a completed bale. The control system predicts a weight of the slice in the intake duct and/or the intake region of the baling chamber derived from the measured relative density values of this slice and the computed correlation function.
