A speed square is provided including a triangular flat plate having measurement markings indicated on at least one face, a T bar affixed to, and extending along, the length of a first side of the triangular flat plate, and an extension element hingedly connected to an end of second side of the triangular flat plate opposite the T bar. The extension element having measurement markings indicated on at least one face, such that the measurement markings of the triangular flat face continue on the extension element.