What is a Speed Square?
Speed Square is the street name (but also a registered trademark of Swanson Tool Company) used to describe a small triangular-shaped tool treasured by carpenters, woodworkers and DIYers worldwide. It’s in the shape of a right triangle. One leg is imprinted with a ruler, the other leg has raised fences along the edges which can “hook’ on the edge of a board, while the hypotenuse contains degree markings which allow the user to mark angles from 0 to 90 degrees. With the fence hooked over the edge of a board, the remaining two sides are ideal for marking 90- and 45-degree cuts, or for guiding a circular saw while making those cuts. The degree markings on the hypotenuse make it especially useful in marking roof rafter angles.
Its small size (each leg is about 7-in. long so it easily fits in a tool belt) and its versatility make the Speed Square a mainstay in most carpenters’ tool belts or tool boxes.