A document stacker (1) for receiving documents from a document processing device (3), wherein the document stacker comprises: a document support (4), and a frame (5), wherein the document support is attached to the frame by a linear guide means configured such that the document support is linearly movable with respect to the frame along a predetermined path of movement (7) inclined to a horizontal plane, and wherein the document stacker further comprises a load cell (14) configured to resist relative movement between the frame and the document support along said predetermined path and to emit an output signal representative of the load applied to the load cell by the document support.