Mechanical & Civil Engineering
Bolt Preload & Tightening Torque Calculator
Calculate required tightening torque for a target bolt preload using the torque coefficient method.
Your inputs
Change any value to update the result instantly.
Tightening torque
30 N·m
Preload force
15,000 N
Bolt diameter
10 mm
Torque coefficient
0.2
What this calculator does
Bolt Preload & Tightening Torque Calculator: Applies the standard shop-floor or joint-design relationship so the force, speed, allowance or strength can be worked out from the process inputs.
What your result means
The headline figure is the process setting or joint strength implied by your inputs. Treat it as a starting point to validate against the tool maker's data and a trial part.
Formula and working
T = K × D × F
- 1
Collect the inputs
Bolt nominal diameter = 10 mm; Target preload force = 15,000 N; Torque coefficient K = 0.2
- 2
Apply the formula
T = K × D × F
- 3
Result
Tightening torque = 30 N·m
Frequently asked questions
Symbols and assumptions
- diameter
- Bolt nominal diameter (mm)
- preload
- Target preload force (N)
- k
- Torque coefficient K
- • Nominal tooling, material and process conditions are assumed; machine, tool-wear and lubrication effects vary in practice.
- • Recommended cutting data always sits inside the tool maker's published envelope, which takes priority.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • This is an educational estimate for learning and checking, not a design deliverable.
- • Real design must follow the governing code or standard for your jurisdiction and be reviewed and signed off by a qualified engineer.
- • Safety factors, load combinations and material certification are the responsibility of the designer, not of this page.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
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