Abstract: A cutter for mat frames which includes a cutter head, including a pair of blade carrying cutter blocks, slidable along a cutter bar and having a plurality of adjustable stops for accurately positioning and cutting of a mat board without over or under cutting. The assembly also includes means to limit the depth of the cut by one of the cutter blocks and means to lock the other cutter block in cutting position. Also included in the cutter is an adjustable handle frame which includes a cutter bar along which the cutter head is guided.