Bolt Stretch Calculator
Elongation at target preload — the gauge-and-micrometer tightening method.
Measuring stretch beats torque ±25% scatter with ±3% accuracy — that's why critical joints (con-rods, turbines) tighten by elongation or angle, never torque alone.
Formula
Bolt Stretch Calculator is a free bolt stretch for design engineers, metallurgists and QA inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Bolt Stretch Calculator
Elongation at target preload — the gauge-and-micrometer tightening method. The calculation implements δ = F·L_grip/(A_s·E) (VDI 2230; Bickford). Measuring stretch beats torque ±25% scatter with ±3% accuracy — that's why critical joints (con-rods, turbines) tighten by elongation or angle, never torque alone.
How to use Bolt Stretch Calculator
- 1Enter Target preload in kN.
- 2Enter Clamped (grip) length in mm.
- 3Enter Stress area in mm².
- 4Enter Bolt E in GPa.
- 5Read Required stretch instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Bolt Stretch Calculator?
- ✓Implements the standard formula — δ = F·L_grip/(A_s·E)
- ✓Reference cited on-page: VDI 2230; Bickford
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Bolt Stretch Calculator use?+
It computes δ = F·L_grip/(A_s·E), per VDI 2230; Bickford. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Measuring stretch beats torque ±25% scatter with ±3% accuracy — that's why critical joints (con-rods, turbines) tighten by elongation or angle, never torque alone.
Where do the material property defaults come from?+
Defaults are standard handbook values (ASM, manufacturer datasheets, the cited standard). Always substitute certified values from your material's test certificate for critical work.
Is the Bolt Stretch Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
Related Engineering tools
Reynolds Number Calculator
Compute Re from density, velocity, pipe diameter and viscosity — with instant laminar/turbulent classification.
● LiveLaminar vs Turbulent Flow Classifier
Classify hydraulic-oil or process-fluid flow regime from kinematic viscosity, line velocity and tube bore.
● LiveBernoulli Equation Solver
Solve downstream pressure between two points from velocities, elevations and fluid density (ideal, lossless).
● Live