Bolt Torque Calculator
Calculate bolt tightening torque from nominal diameter, desired clamp load (preload) and nut factor for dry or lubricated threads.
Leave blank to use 75% of proof load for the grade.
Formula
T = K × D × F; typical preload F ≈ 75% × proof strength × tensile-stress area (A_t ≈ 0.75 × πD²/4)