Bolt Torque Calculator
Static · formula-only · worked example computed when this page was built · no live data
The Bolt Torque Calculator finds the tightening torque and clamp preload for a bolt from its size, grade, and target preload. Example: for eight M16 grade-8.8 bolts torqued to 75% proof load under a 40 kN external load, Tightening torque = 218.6 N·m, Preload per bolt = 68.3 kN, Stress utilisation = 75 % (per ISO 898-1:2013 | VDI 2230).
How it works
Computed from your inputs per ISO 898-1:2013 | VDI 2230. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (Mechanical & Machine Design)
Inputs: eight M16 grade-8.8 bolts torqued to 75% proof load under a 40 kN external load.
| Result | Value |
|---|---|
| Tightening torque | 218.6 N·m |
| Preload per bolt | 68.3 kN |
| Stress utilisation | 75 % |
Computed by WorkHive's calculation engine when this page was built; standard: ISO 898-1:2013 | VDI 2230.
How to use this calculator
- Read the worked example. It uses eight M16 grade-8.8 bolts torqued to 75% proof load under a 40 kN external load and shows every number in the method.
- Follow the formula with your own figures: it returns Tightening torque, Preload per bolt, Stress utilisation, computed per ISO 898-1:2013 | VDI 2230.
- To compute interactively, open the Bolt Torque Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a bolt torque and preload calculator?
The Bolt Torque Calculator is a free online tool that finds the tightening torque and clamp preload for a bolt from its size, grade, and target preload. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following ISO 898-1:2013 | VDI 2230. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive Bolt Torque Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.