The invention relates to a document shredder (1), comprising a cutting unit (4), a motor (3) for driving the cutting unit (4), and a motor control system (2). The document shredder (1) additionally has a path measuring device (13), wherein the motor control system (2), by means of the path measuring device (13), determines the length of the already shredded portion of the document to be shredded, and the motor control system (2) controls the motor (3) in dependence on the measured length of the already shredded portion of the document to be shredded.