A system for determining knife usage. The system includes an infeed cutter including a cutter rotor, a knife drawer, and a plurality of knives extending through the knife drawer. The cutter rotor is mounted above the knife drawer such that a cutting zone for crop material is defined. The system further includes a measuring device configured to measure a quantity which is representative for the couple exerted by the cutter rotor on crop material going through the cutting zone of the infeed cutter, a controller configured to control the measuring device for measuring values for the quantity at consecutive moments in time, and a knife usage determining module configured to determine knife usage based on the measured values.
