Calculators

Each one shows its assumptions beside the result, carries its derivation, and cites the standard and edition every value comes from.

Calculator
Preload and tightening torque
Preload and tightening torque for an ISO metric bolt, from its thread, property class, nut factor and target fraction of proof load.
Cites ISO 898-1:2013ISO 68-1:2023ISO 261:1998ISO 262:2023
With preload sensitivity to the nut factor, preload stress against the class's strengths and thread geometry and the stress area.
Rev E, 2026-09-26