Abstract: A sheetrock panel cutting device that is attachable to the end of a conventional metal tape ruler and uses that same tape ruler to not only measure the opening but to also guide the cut of a sheetrock panel while accomplishing both these functions without removing the tape ruler therefrom. A utility knife is inserted into a preformed slot in a base plate which causes the blade of the knife to be aligned juxtaposed to the right angle clip of the tape ruler. The blade protrudes through the base plate and which is directly mounted against the right angle ruler end clip. The device is used to cut a rectangular panel of sheetrock of predetermined size from a full sheet by holding the utility knife, which is positioned in the device, against the sheetrock paper surface with one hand while grasping the metal tape ruler surface, at a previously measured position on the tape, with the other hand against the edge of the sheetrock panel.