Shear stress is defined as the internal forces acting on an object when a force acts parallel to the face of the material, whereas shear strength is the maximum force the object can handle before becoming structurally compromised. Calculating the shear strength of a bolt can be particularly important, especially during construction work, as very large stresses can cause the bolts to fail.
Multiply the failing force of the bolt (the maximum force the bolt can sustain before failure) by 4. For example, if the failing force is 2 Newtons (N), then the result will be 8 N. Call this result A.
Square the diameter of the circular component of the bolt, and multiply by the constant pi (3.14159). For example, if the diameter of the bolt is 0.1 meters (m), squaring gives 0.01 meters squared (m^2), and multiplying by pi gives 0.031459. Call this result B.
Divide result A by result B. In our example, dividing 8 N by 0.0314159 gives 255 Pascals (Pa). This is the shear strength of the bolt.