Boltspan

Preload, torque and fatigue

Purpose-Built

A transparent bolted-joint calculator for preload scatter, torque, joint stiffness, load fraction, separation, proof margin, fatigue, and tightening sequences.

Core Features

Metric thread stress-area library
Torque-preload scatter envelope
Bolt/joint stiffness model
Separation and proof margins
Sequence and inspection worksheet

Private by Design

No account, subscription, ads, tracking, third-party analytics, or developer-operated backend. Core features work offline, and your work stays on device unless you deliberately share or export it.

Use It Responsibly

Engineering screening only. Confirm material, lubrication, thread engagement, embedment, temperature and governing code.