How to use the bolt torque to preload calculator
Estimate the clamp force a bolt develops from the tightening torque. Enter tightening torque, nut factor, bolt diameter in the fields above; the preload force are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “bolt preload”, “torque to tension”, “how tight should a bolt be”, “calculate bolt torque to preload”, “find preload force”.
Formula
Variables
- Tq — Tightening torque (N·m)
- K — Nut factor
- d — Bolt diameter (mm)
Worked example
With tightening torque = 25 N·m, nut factor = 0.2, bolt diameter = 10 mm, the calculator gives preload force ≈ 12,500 N; preload force ≈ 12.5 kN.
Frequently asked questions
What is the bolt torque to preload calculator used for?
Estimate the clamp force a bolt develops from the tightening torque. It helps with questions such as “bolt preload”, “torque to tension”, “how tight should a bolt be”.
What is the formula for the bolt torque to preload calculation?
Preload force (N) = Tq / (K × d / 1000). Preload force (kN) = [Preload force] / 1000. Here Tq is tightening torque (N·m), K is nut factor, d is bolt diameter (mm).
What inputs do I need for the bolt torque to preload calculator?
You need tightening torque in N·m, nut factor, bolt diameter in mm. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the bolt torque to preload calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the bolt torque to preload result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.