Bolt Bearing Stress Calculator

Projected bearing area

Bearing stress between a bolt and the plate it passes through is calculated over the projected area of contact, not the curved surface area. For a cylindrical bolt shank bearing against a flat plate, this projected area is simply the bolt diameter multiplied by the plate thickness.

This calculator checks average bearing stress only. It does not account for hole clearance, non-uniform contact pressure at the hole edge, plate bending, or combined bearing and shear-out failure at the edge of the plate. Bearing stress should be checked alongside bolt shear stress and plate edge distance for a complete joint design.

If an allowable bearing stress and safety factor are entered, the calculator divides the allowable bearing stress by the safety factor to get a design allowable stress, then compares the calculated bearing stress against that design allowable to give the utilisation ratio. Leaving the safety factor blank, or entering 1, uses the allowable bearing stress directly with no additional margin applied.