Engineering tool · V0.6
Bolt Torque / Preload Estimator
Use the simple nut-factor relationship T = K·F·d to estimate preload from torque or torque from a target preload. It is a concept-stage estimator because real torque–tension scatter is strongly affected by friction, lubrication, coatings and joint details.
Concept-stage assumption only; actual K depends heavily on friction conditions.
Estimated preload—
Estimated torque—
Approx. tensile stress—
Enter assumptions to calculate.
T = K × F × d
T in N·m, F in N, d in metres
T in N·m, F in N, d in metres
Do not use this simple relationship by itself to specify a safety-critical tightening procedure. Real bolted-joint design can require thread geometry, bearing friction, preload scatter, embedment, separation/slip checks, fatigue, temperature and a validated tightening method.