Tensile loading
Initial preload, load at yield, and load reserve for metric bolted joints (no friction).
Mechanical Calculators
Bolt and fastener calculations for metric screw joints.
Designing a bolted joint is a chain of connected questions: how much clamping force do I need, how much preload can the bolt deliver, what torque installs that preload, how does an external load split between bolt and clamped parts, and will the joint survive millions of load cycles? The seven calculators below cover that chain end to end for metric coarse threads M6–M42, using ISO 724 / DIN 13 thread geometry and EN ISO 898-1 strength classes (3.6–12.9).
A typical workflow: size the bolt with the tensile loading tool, find the assembly torque with the tightening torque calculator (or its inverse, the maximum torque at a stress limit), estimate the load-sharing factor with the joint stiffness tool, then check dynamic behaviour with the joint diagram and fatigue strength calculators. The thread stripping tool verifies the engagement length in nuts and tapped holes. Every calculator includes the underlying theory, equations, a worked example, and an FAQ on the same page.
Tightening torque (metric)
Preload and tightening torque for metric screw joints using ISO geometry and EN ISO 898-1 strengths.
Maximum tightening torque
Maximum tightening torque to a target equivalent stress, including stress relaxation.
Basic joint diagram
Bolt joint under dynamic loading — preload, load fluctuation, and clamping force.
Fatigue strength
Endurance strength and allowable load fluctuation for bolted joints.
Joint stiffness factor
Bolt and clamped-part stiffness, and load-sharing factor Cm.
Thread stripping strength
Shear area and stripping load for a given engagement length.