Bolt Torque Calculator
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.
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 live by WorkHive's calculation engine; standard: ISO 898-1:2013 | VDI 2230.
How to use this calculator
- Enter the figures for the duty you are sizing: the worked example below uses eight M16 grade-8.8 bolts torqued to 75% proof load under a 40 kN external load.
- The calculator returns Tightening torque, Preload per bolt, Stress utilisation, computed per ISO 898-1:2013 | VDI 2230.
- Check the worked example to confirm the method matches how you would do it by hand, then run your own numbers in the interactive tool.
FAQ
What is a bolt torque and preload calculator?
The Bolt Torque Calculator is a free online tool that computes 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's engineering calculators are free to use, no sign-up needed for the tools. 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, no sign-up needed for the calculators.