Torque to Tension Calculator
SI
Imp
Imperial
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Solve for
Use the same nut-factor equation in either direction.
Find bolt tension from torque
Find torque from target tension
Applied torque
(T)
Tightening torque.
N·m
Target tension
(F)
Desired bolt preload / clamp force.
N
Nut factor
(K)
≈0.20 dry, 0.15 lubricated, 0.10 anti-seize.
Nominal bolt diameter
(d)
Nominal thread diameter.
mm
Results
Default result
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Bolt tension / preload
(F)
15,000
N
15 kN · 3,372 lbf
Using K = 0.2.
Also computed
Required torque
(T)
30
N·m
Method notes
2 notes
Short-form torque-tension relation: T = K · F · d. The nut factor K rolls thread and under-head friction into one empirical number.
Torque control is an estimate, not a precision preload method. Plating, lubricant, washer hardness, thread condition and reuse can move K enough to change tension dramatically.
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