Free Bolt Torque Calculator
Calculate the required tightening torque for a bolt to achieve a target preload (clamp force).
kN
mm
Required Torque
160.0 N-m
Required Torque vs Target Preload Force (F)
Bolt Torque-Preload Relationship
Torque applied to a bolt creates axial preload that clamps the joint together.
Formula
T = K F d
where T is the tightening torque, K is the nut factor (torque coefficient), F is the desired preload, and d is the nominal bolt diameter. K depends on lubrication: dry steel K = 0.20, lightly oiled K = 0.15, anti-seize compound K = 0.12.
Example Calculation
An M16 bolt needs 50 kN preload with K = 0.2 (dry).
- 01F = 50 kN = 50,000 N
- 02d = 16 mm = 0.016 m
- 03T = 0.2 x 50,000 x 0.016 = 160 N-m
Frequently Asked Questions
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