Shearing stress, denoted by the Greek letter tau (τ), is stress caused by forces acting transversely on an object. These forces create internal ones within the entity in the plane where the external forces are applied. The resultant of these internal forces is the shear in the section.

The average shearing stress can be calculated by dividing the shear by the area of the cross-section.

However, this is an average value as the distribution of shearing stress across a section varies. It can range from zero at the surface to a maximum far exceeding the average.

Elements like bolts, pins, and rivets, often used to connect machine components or structural members, frequently experience shearing stresses. For instance, tension forces exerted on two plates connected by a bolt may lead to shearing stresses in the bolt's section lying between the plates' surfaces, resulting in shear equal to the tension force.

In complex scenarios, such as splice plates connecting other plates, shear occurs in two planes of each bolt, known as double shear. The average shearing stress in each plane is determined by dividing the applied force by twice the area.