Enter the tensile shear area of the bolt and the proof load of the bolt into the calculator to determine the bolt preload. The calculator will provide two outputs, one for connections requiring re-use and one for permanent connections.

The following formula is used to calculate a bolt preload force.

F = c * A * S
• Where F is the preload force
• c is a constant (.75 for reuse connections, .89 for permanent connections
• A is the tensile shear area of the the bolt
• S is the poof load of the bolt

To calculate the bolt preload, multiply the constant by the shear area and the proof load.

A bolt preload is defined as the total tension force created in a fastener, in most cases a bolt, when it is tightened.

The optimal preload is reached when the working load placed on the bolt is distributed to the installation material, or in other words, the materials the bolt is holding together.