Rafter squares measure and lay out straight, 45° angled, and 90° angled lines. Also known as speed squares, their flanged edge sits against a workpiece edge to check whether materials are square and to anchor the tool when marking lines. The flanged edge also provides a pivot point to measure and mark a range of angles. Their diagonal leg assists with marking rafter, trim, and stair angles. They are also used with plumb bobs when finding pitch on roof rafters and marking level lines along a plumb line.

Framing squares set their two legs at a right angle for measuring and marking angles as well as vertical and horizontal lines. Also known as steel squares, they set up framing, guide cuts for stair stringers, lay out rafters, and more.

Drywall squares provide a measuring stick and straight edge for scoring drywall, plasterboard, and other materials. Also known as drywall T-squares, their crossbar head holds them in place along the edge of material while making the cut. These squares are generally larger and more resistant to rough use than drafting T-squares.

Try squares assist with checking work for squareness, marking internal and external right angles, and laying out perpendicular lines. Their handle holds them in place along workpiece edges, and their fixed blade sits at a 90° angle to the handle to guide measurements, markings, and cuts. Also known as tri squares, they are commonly used for aligning framing, building staircases, and setting up tools and machinery.

Sliding T-bevels lay out a range of angles and copy angles to transfer them from one workpiece to another. Their blade slides and pivots along the handle, then locks in place with a thumbscrew to set an angle. They are commonly used in woodworking and carpentry to mark angles for making miter cuts, especially those with angles less than 90°.

These accessories adapt layout and T-squares for specific tasks.