Abstract: Disclosed is a tool for marking tiles having a predetermined thickness, so that the tiles may be cut precisely to enable them to be placed adjacent each other and spaced apart a predetermined, uniform, distance corresponding to the thickness of a desired grouting thickness. The tool includes a generally flat, elongated, rectilinear bar having a pair of opposed ends, a pair of opposed sides, and generally flat top and bottom opposed faces. A plurality of different sized slide elements are selectively used with the bar depending of the desired thickness of the grouting. Individual ones of the slide elements are adapted to be carried by the bar and movable along the length of the bar between the ends and removed from the bar by sliding off an end. Each of said slide elements have a body member which is supported by the top face and has a pair of opposed arms extending along and bearing against the sides. The arms have a height less than the thickness of the tile.