Abstract: A layout tool for defining points on rolled metal H beams comprises a U shape frame having a hand hold in the bight of the U. One leg of the frame is longer than the other and terminates at its end in a stabilizing and guide member extending perpendicular thereto. The guide member has a flat wear surface adapted to be positioned against the working line of the beam on the external surface of the beam to which all measurements are taken. The other leg of the frame slidingly supports in a channel provided therein a T scale having a flat stabilizing base member adapted to rest on the web of the beam. A locking mechanism is provided in the second leg which includes a thumb screw for locking the scale in position in the channel. The scale is disposed at right angles to the legs and the stabilizing and guide member such that the layout tool allows orthogonal lines to be scribed in any one position of the tool.